Effects of International Volunteering and Service: Individual and Institutional Predictors

Despite unprecedented recent expansion of international volunteering and service (IVS), there has been relatively little research on impacts. This paper proposes a conceptual model for impact research based on existing research evidence published in English. The model suggests that outcomes for host communities, volunteers, and sending communities vary depending on individual and institutional attributes and capacity. How institutions structure and leverage individual capacity inﬂuences who participates and how they serve, and shapes the impact of volunteer action. The conceptual model provides directions for future research. Le mode`le conceptuel fournit des perspectives pour de futures recherches.

Résumé En dépit de l'expansion sans précédent du VI (Volontariat international), il y a eu relativement peu de recherches sur ses impacts. Cet article propose un modèle conceptuel sur la recherche d'impact se basant sur la preuve de recherches existantes publiées en anglais. Le modèle suggère que les résultats pour les communautés hôtes, les volontaires et les communautés envoyées varient selon les attributs et la capacité des individus et des institutions. La façon dont la structure des institutions et les influences sur la capacité des individus, influence ceux qui participent et la façon dont ils servent et donnent forme à l'impact de l'action volontaire. Le modèle conceptuel fournit des perspectives pour de futures recherches.

Introduction
The twenty-first century is witnessing an unprecedented expansion of international volunteering and service (IVS), both in numbers of volunteers and sponsoring organizations (Clark 2003;McBride et al. 2003;Davis Smith et al. 2005;Randel et al. 2004;Lough 2006;Rieffel and Zalud 2006;Allum 2007;Hills and Mahmud 2007;McBride and Sherraden 2007;Peace Corps 2007a;Plewes and Stuart 2007;. Despite the growth of IVS, there has been relatively little research on impacts (Woods 1981;Carson 1999;European Commission 2004;Hills and Mahmud 2007;Machin 2008). Proponents suggest that IVS encourages large numbers of ordinary people to get involved in global affairs, and to promote global peace, international understanding, and make tangible contributions to the well-being of people around the world (UNV 2002a, b). Critics contend that IVS tends toward imperialism, reinforcing existing inequalities, or at best, is ineffective in the face of grave global challenges (Brav et al. 2002;Roberts 2004;Simpson 2004;Plewes and Stuart 2007).
This paper develops a conceptual model for impact evidence, using existing evidence to identify key categories and relationships. 1 The model suggests that outcomes for host communities, volunteers, and sending communities will vary depending on volunteer attributes and individual capacity, as well as program attributes and institutional capacity. 2 Volunteer attributes refer to the sociodemographic characteristics of the volunteer corps. Individual capacity refers to the knowledge, skills, and motivation that individuals bring to the volunteer experience that affect their effectiveness and ability to meet placement goals and objectives. Program attributes refer to the features of the volunteer-sending and volunteerhosting programs. Institutional capacity addresses the context of the service experience, defines who participates and how they serve, influences the ability of the institution to leverage individual capacity, and shapes the impact of volunteer action. Figure 1 (above) graphically depicts these relationships and the following sections analyze them in greater detail. 3 The model provides directions for future research, discussed in the final section.
We begin with a definition: IVS is an organized period of engagement and contribution to society by volunteers who work across an international border, in another country, or countries. IVS may be sponsored by public or private organizations, it is recognized and valued by society, and volunteers receive little or l a n o i t a n  r  e  t  n  I  l  a  u  d  i  v  i  d  n  I   g  n  i  r  e  e  t  n  u  l  o  V  l  a  n  o  i  t  u  t  i  t  s  n  I  d  n  a  d  n  a  r  e  e  t  n  u  l Costanza and Geudens (2003) spell out the roles of each of these. 3 This conceptual model borrows from a schema of ''productive aging'' proposed by Morrow-Howell et al. (2001). Voluntas (2008) 19:395-421 397 no monetary compensation (Sherraden 2001). 4 This definition excludes volunteering within national boundaries, as well as mutual aid and military service.

Volunteer Attributes and Individual Capacity
Individual volunteer socio-demographic characteristics affect the quality and type of service and its outcomes. The demographic and socio-economic profile of international volunteers make a difference in the likelihood of volunteering and volunteer effectiveness (Waldorf 2001;Greenwood et al. 2005;Allum 2007).

Volunteer Attributes
Research on volunteers from North America and Europe finds that international volunteers tend be young, educated, affluent, and white (Williams 1991;ECOTEC 2000;Jones 2004;). Older adults, people with low incomes, ethnic and racial minorities, people with physical disabilities, and those who cannot take time off their jobs may have less opportunity to volunteer internationally (ECOTEC 2000;Brav et al. 2002;Sygall and Lewis 2006;Ludlam and Hirschoff 2007;Peace Corps 2007b). Relatively little research addresses the influence of volunteer religious affiliation and practice, even though large numbers of volunteers serve abroad with religious organizations. The composition of the volunteer corps likely affects IVS outcomes. For example, older and trained volunteers may bring greater expertise to a project (Mitka 2006), but they may be less flexible and open to a reciprocal relationship with hosts than younger, untrained volunteers (Waldorf 2001). In another example, gender of volunteers may affect whether women or men in the host community receive benefits from international volunteers (Cohn and Wood 1985).

Individual Capacity
Knowledge and Skills The importance of knowledge and skills depends on the goals of the volunteer project. Some IVS projects require more enthusiasm, energy, and goodwill than specific knowledge and expertise. In work camps that construct trails or build latrines, youthful energy and a desire to engage in cross-cultural experience are necessary, and may help to prepare volunteers for more technical placements in the future (Thomas 2001;Dumélie et al. 2006). Technical assistance and professional service projects require volunteers with training and experience (VSO 2002;Daley and Winter 1978). In humanitarian aid projects, for example, less-skilled international volunteers may offer few advantages, and in fact may be a liability (Dumélie et al. 2006).
Motivation and Effort People are motivated to volunteer for different reasons, which may affect participation, volunteer activities, and outcomes (Mueller 1975;Law 1994;Carson 1999;Wilson 2000). Motivation to volunteer may vary by race and ethnicity (Sharma and Bell 2002). People in different life stages may also have different motives for volunteering. According to Erik Erikson's (1968) theory of psychosocial development, older adults may be motivated to stay active in retirement or to ''give back.'' Youth, in contrast, tend to volunteer internationally to gain a broader perspective on the world, to contribute to society and help others, have an adventure, take a break from school or work, meet people and have fun, acquire skills, enhance a resume, or get a job (Gaskin 2004;Jones 2004;MacNeille 2006;). Motives may affect outcomes. For example, volunteers focused primarily on personal benefit may have less to offer host organizations and communities (Anheier and Salamon 1999;Rehberg 2005).
Prior Volunteering and International Experience Prior volunteering and international experience may affect individual motivation and preparation, including ''cultural proficiency'' for IVS (Cohn and Wood 1985, p. 170;see also, VSO 2002;Rehberg 2005;Gran 2006). Prior experience may also reduce objections by family and peers, which researchers identify as barriers to IVS (Sharma and Bell 2002;Gaskin 2004

IVS Program Attributes and Institutional Capacity
Volunteer characteristics and individual capacity matter in the decision to volunteer internationally and they likely also affect IVS outcomes. However, the opportunity to volunteer abroad and the structure of the volunteer experience also has important effects. These are institutional questions. One aspect of the institutional context is ''macro'' features that influence the likelihood of IVS, such as tax breaks for philanthropy or the cost of international travel. The focus in this paper, however, is at the mid-range, focusing on the organizations that sponsor and facilitate international volunteering, and the ways that IVS programs encourage, inform, and facilitate participation. Organizations shape the IVS experience, setting the stage for individuals and groups to participate if and when they are inclined. (It is also likely that volunteers influence IVS programs, although we find little research evidence.) Therefore, the key to shaping opportunity to engage in IVS-and the outcomes of IVS-are individual and institutional (Meier 2006). A key to predicting outcomes, for example, may be the match between volunteer and program goals ).

IVS Program Attributes
Type of Organization IVS programs may be public, nonprofit (nongovernmental), or private for-profit. The type shapes programs and influences IVS outcomes (Eberle and Sherraden 1990;Henderson 2002). Within each of these sectors are many different kinds of IVS programs. For example, governments may operate IVS programs directly or indirectly through subsidies to the private sector. Nonprofit organizations operate the largest number of IVS programs (McBride et al. 2003), and vary widely in size and sponsorship, and include secular and faith-based groups. Similarly, for-profit IVS may include some eco-tourism, gap-year, and corporate volunteer programs.
There are often several layers of organizations, which may influence the nature of IVS activity and impacts (Sherraden et al. 2006). International volunteers may be sent by one organization (sending organization) and received by another (host organization) that places volunteers and oversees service activities. Sometimes sending organizations do most of the supervision and guidance in the field. In other cases, instead of a direct relationship with community-based host organizations, IVS programs contract with intermediaries that coordinate activities in one or more countries, including selecting local host organizations and coordinating volunteer placement and other logistics. This is the case of many workcamp programs. Corporate international volunteer programs are another example. They report multiple benefits of using intermediaries, including volunteer coordination, local credibility, and improved cultural insight (Hills and Mahmud 2007;Vian et al. 2007a, b). This arrangement permits broader reach by an IVS sending program and may increase local relevance, but possibly diminish IVS sending program control and attenuate IVS program goals.
Program Mission and Goals Each organization has a mission and goals, which shapes how it utilizes volunteers and its program outcomes. As Steven Powell and Esad Bratović (2007) suggest, ''you get the impact you program for' ' (p. 42). IVS programs tend to emphasize building international understanding or development aid and humanitarian relief, although in practice, there is overlap between these two types of goals (Woods 1981;Davis Smith et al. 2005;Devereux 2006;Sherraden et al. 2006). 5 Programs emphasizing international understanding focus on ''contact between people'' (Randel et al. 2004, p. 5). The emphasis is on international experience and fostering cross-cultural skills and tolerance, global awareness and international solidarity, civic engagement, personal development, and international peace and understanding among volunteers and hosts (Randel et al. 2004;Spence 2006).
Programs emphasizing development aid and humanitarian relief focus on the expertise and experience that volunteers bring to their assignments. Cross-cultural learning and international understanding tend to be secondary compared to service delivery, and knowledge, skill, and technology transfer. However, some suggest that IVS poses a positive alternative to top-down development models by using both technical skills and an ability to connect and build trust (Greenwood et al. 2005;Leigh 2005;Rockliffe 2005;Devereux 2006;Werna and Schneider 2006). In the case of long-term development volunteering, writes Peter Devereux, ''it is a form of international cooperation that can question power and economic structures and bring relational values and intimacy to the fore amongst divergent actors in different parts of the world' ' (2006, p. 2). Therefore, compared to salaried development officials, volunteers in development projects may be more effective because they have fewer expectations for personal gain and greater local accountability (Jedlicka 1990, p. 4;Devereux 2008).
Program Sponsorship, Funding, and Size The type of organization has implications for funding levels and program size. Government sponsored IVS programs, while less numerous, tend to be larger and better funded. Nonprofits receive funding from a variety of sources, including government, foundations, corporations, religious organizations, service clubs, and donors, but they often also must charge participant fees. Private for-profit programs typically receive little or no public funding. Corporate IVS program are often located within corporate responsibility programs (Hills and Mahmud 2007;Vian et al. 2007a, b). For-profit programs also include rapidly growing eco-tourism and ''gap year'' programs and tend to rely on participant fees, although we know relatively little about them (Jones 2004). 6 Finally, sponsorship has implication for IVS mission and goals. Secondary (and even primary) goals may reflect the sponsor's mission (Sherraden et al. 1990). For example, government sponsored IVS may be aimed at state interests; corporate sponsored IVS may be aimed at public relations or market reach; nonprofit sponsored IVS may be aimed at international advocacy efforts; church affiliated IVS may be aimed at proselytizing; and for-profit IVS programs may be looking directly at the bottom line.
Recruitment Policies Programs shape the volunteer corps through recruitment strategies. Eligibility requirements may be highly selective or they may be quite.

Institutional Capacity
In large measure, IVS program attributes shape the institutional capacity of sending organizations to launch IVS action (Fig. 1). Research suggests several conceptual categories for analyzing institutional capacity, including resources, access, incentives, information, facilitation, and accountability.
Resources The ability of sending, host, and intermediary organizations to cover costs and coordinate IVS activities may shape volunteer effectiveness and outcomes of service (SOS 1999b). While volunteering can be cost effective, it nonetheless requires significant resources. 7 Organizations in sending and receiving countries provide orientation, language training, supervision, and support for volunteers. Volunteers have to be lodged, fed, and nursed back to health. Health care and security matter to volunteers (Ludlam and Hirschoff 2007).
Access Studies suggest that international volunteers tend to originate in wealthier countries (e.g., North America, Europe, Japan, Australia), and favor majority citizens from those countries (Allum 2007). These qualities may influence IVS program capacity, including IVS program capacity to achieve an international focus (Pastor 1974).
A number of factors affect who can and does volunteer, including eligibility, roles, access to information, organizational affiliation, procedures, social protection, time availability, and an appropriate volunteer opportunity (CEC 2001;AVSO 2004;European Commission 2004;Gaskin 2004;Jones 2004;Rehberg 2005;Gran 2006;Hong et al. 2008). Studies suggest that IVS increases when programs provide direct access to participation. In a study of corporate volunteering, for example, Dick de Gilder and colleagues (2005) find that ''the total number of people and the total number of hours'' volunteering increase for ''all kinds'' of employees when offered access to the opportunity to volunteer (p. 150).
Although existing research suggests that volunteers tend to be a homogeneous group, IVS programs that actively recruit volunteers from diverse backgrounds may have certain advantages. Inclusive programs are more likely to challenge preexisting stereotypes in host communities (Sharma and Bell 2002). Likewise, volunteers from disadvantaged circumstances may benefit significantly more than those from privileged backgrounds (Adams et al. 1996;Schröer 2003).
Internationality Another way to distinguish among IVS programs is the direction of service and laterality. In unilateral IVS the flow of volunteers is one-way: an organization sends a volunteer from country A to country B. This is perhaps the most common way of organizing international service (Sherraden et al. 2006). Bilateral and multilateral IVS are partnerships among two or more organizations from two or more countries to implement an IVS program. Transnational IVS is a particular form of multilateral voluntary service, but it is set apart because the international dimension is intensified. While most multilateral programs place volunteers from two or more countries to serve together in one country, in transnational programs, volunteers from two or more countries serve in a multinational group on consecutive projects in more than one country Sherraden 2007).
Incentives Economic issues may also affect the propensity to volunteer abroad and the outcomes of service, suggesting the possible influence of incentives, such as remuneration and compensation for volunteering. Financial concerns may be more acute in international compared to domestic volunteering, which costs less and can be accomplished alongside work and school. Financial concerns may differ according to the age and other characteristics of volunteers. For example, older and more experienced volunteers may be particularly concerned about tax issues and health coverage (Ludlam and Hirschoff 2007). Participation fees and opportunity costs of volunteering suggest potential importance of a volunteer social protection package to expand the volunteer pool (Sharma and Bell 2002;Jones 2004;Gran 2006). Remuneration or compensation, in the form of stipends, academic credit, recognition, or other incentives, may encourage a more diverse volunteer pool and greater volunteer effort in the field (Moskwiak 2005). Programs that provide minimal salary and accommodation comparable to local wages, may encourage trust and understanding in the host community (VSO 2002), compared to those who offer perks unavailable to local residents (Rehnstrom 2000).
Training, Support, and Supervision Orientation, language training, supervision, coaching, peer and social support, and collective reflection also may influence effectiveness (Dumélie et al. 2006;Eyler and Giles 1999;Grusky 2000;CEC 2001;Costanza and Geudens 2003;Sherraden and Benítez 2003;Simpson 2004;Mutz and Schwimmbeck 2005;Hoksbergen and Veenema 2007;. Volunteer placements often require significant cultural adaptation and adjustment to different and sometimes difficult work and conditions. Researchers have also linked post-program debriefing and follow-up for former volunteers to positive outcomes for volunteers (Grusky 2000;Keesbury 2003).
Accountability Like development programs generally, volunteer programs may be more effective when they are accountable to volunteers, host organizations, and host communities (Cleaver 1999;Jones 2004;Engel 2006;Ludlam and Hirschoff 2007;Devereux 2008). In other words, IVS may be more effective when it is meaningful and responsive to volunteers, reflects community priorities, and involves community residents and leaders in projects and decision-making. Accountability requires effective program evaluation and communication with stakeholders.
Host organizations, for example, may play a minor or major role in determining objectives, selecting volunteers, choosing IVS activity, or supervising volunteers. Compared to IVS programs with low levels of accountability and community involvement, programs that are locally accountable may adjust IVS service to local conditions, gain acceptance and community involvement, and meet organizational and community needs (VSO 2002). In this model, volunteers do not act as managers and experts, but colleagues and team members, thereby encouraging mutual learning and reciprocity in skill sharing, while minimizing paternalism and reducing competition (Daley and Winter 1978;Rockliffe 2005). However, they may also have less power vis-à-vis outside organizations (Devereux 2006;Dumélie et al. 2006).
Organizational Networks Organizational networks can connect host organizations to local and foreign partners for resources, advocacy, media work, lobbying and campaigning, and other forms of empowerment. Vertical networks or ''broker partnerships'' with companies, NGOs, or universities encourage participatory decision-making at higher levels, while reducing donor-dependence and advocating for policy changes (Acevedo 2002;VSO 2002). Horizontal networks between local people and organizations, or between host organizations and volunteers' home community organizations, can support the growth of civil society in both countries, while increasing knowledge of development issues in the sending country (VSO 2002).

International Volunteering and Service Action
Volunteer attributes and capacity, along with IVS program attributes and institutional capacity come together in IVS action. Action is shaped by type of service activity, length and continuity of service, group or individual setting, direction of service and reciprocity, and the level of cross-cultural contact and immersion.
Service Activity Volunteers engage in a broad range of service activities internationally (Pinkau 1981). Although studies roughly identify IVS activities, none is comprehensive and worldwide. An assessment of 103 international volunteer programs, indicate main activities are educational services (85%), human and social services (80%), community development (75%), and environmental protection (73%) (McBride et al. 2003). 8 A Peace Corps study finds education to be the most common volunteer activity (35%), followed by health (21%), business development (16%), and environment (14%) (Peace Corps 2007b). A UK study of gap-year programs estimates the most common types of activities performed by gap-year participants are community-based work (37%), teaching (15%), and conservation and environment (15%) (Jones 2004).
With only a rough idea of the distribution of IVS activities worldwide, we know even less about the benefits and drawbacks. For example, a focus on technology transfer by professionals may backfire if volunteering becomes more like development aid, thus losing the non-monetary advantage and reciprocal relationships that lie at the heart of volunteering (Keesbury 2003;Devereux 2006;Engel 2006).
Length and Continuity of Service IVS programs range in duration from one-week to one or more years, and although short-term placements are growing (Allum 2007), the average appears to be six to seven months or more (McBride et al. 2003;Jones 2004;Lough 2006). Although research to date is inconclusive, outcomes may vary by length of service. Placements of different duration may accomplish different objectives.
Some researchers suggest that long-term placements have greater development potential (White and Cliffe 2000;Spence 2006), including potential for exchange of technical skills, knowledge, and experience between volunteers and local residents (UNV 2002c;Devereux 2006;Dumélie et al. 2006). However, international volunteers may encourage host organizations to substitute volunteers for local volunteers or employees. Long-term volunteers, who have more time to learn about and become trusted by the community, may be able to challenge imperialism, elitism, and the modernization paradigm of development (Devereux 2006).
Depending on the circumstances, short-term placements can be successful in promoting cross-cultural understanding or technology transfer. Short-term placements benefit volunteers (Purvis 1993;Jones 2005;Devereux 2006), but the benefits to host organizations and communities is less clear, especially if the focus is on volunteers more than host communities (Simpson 2004). Short-term placements may be less cost-effective (Dumélie et al. 2006), and may interrupt continuity of service, a controversial issue in volunteer studies (Keesbury 2003;Laleman et al. 2007). However, consecutive volunteer placements potentially override some deficiencies in the short-term IVS model. Further, short-term service may have potential to engage skilled and professional volunteers (Allum 2007), and may lead to longer volunteering in the future (Dumélie et al. 2006).
Group or Individual Placements Like length of service, individual or group placements may lead to different outcomes. Individual placements may encourage greater volunteer-host interaction, but require more resources. Group placements offer increased economies of scale that result in more volunteer hours, possibly increasing effectiveness. However, group placements may inhibit development of relationships with local hosts and reduce cultural immersion, meaningful contact, and opportunity for volunteers to learn language and customs (Sherraden et al. 2006). This may be key if cultural immersion leads to more appropriate program implementation and volunteer effectiveness. In other words, volunteers in a group placement may be able to make a significant tangible contribution (build a school), but volunteers and local residents may gain little in cross-cultural understanding.
Ethnic, racial, and national diversity within group placements may overcome some of the limitations of co-nationals serving together in groups. In diverse groups, volunteers develop greater cultural awareness, and they may respond to host communities more effectively and with greater sensitivity and competence than homogeneous volunteer groups (Lewis 1999;Sharma and Bell 2002;Peace Corps 2005a). Broader representation among volunteers may also have positive effects in the country of origin (sending country) through greater diffusion of IVS effects across society (Peace Corps 2005b).
Direction of Service and Reciprocity Geographic direction of volunteering may also affect outcomes. Most programs are unidirectional; in other words, volunteers travel from one country to another to volunteer. Moreover, volunteers tend to originate in wealthy countries and volunteer in poor countries or other wealthy countries. As Waldorf (2001) points out, voluntarism ''is a fairly easy choice in our affluent society… but developing countries cannot afford this luxury'' (p. 5).
In recent years, however, there are growing opportunities for volunteers from poor countries to serve abroad (VSO 2002;Randel et al. 2004;UNV 2004;Davis Smith et al. 2005;Rockliffe 2005;Devereux 2006;Allum 2007). However, it remains relatively rare for volunteers from poor countries to volunteer in affluent countries (Moskwiak 2005;Rockliffe 2005). This pattern suggests differential access to IVS opportunities depending on country of origin. It also suggests that skill and technology transfers and cross-cultural experiences are largely North-to-South rather than being reciprocal. Some service is multilateral; in other words, volunteers from two or more countries travel to volunteer placements in two or more countries (Sherraden et al. 2006;Allum 2007). 9 Some programs are multilateral and reciprocal. Among the most well known are Canada World Youth, Swedish World Youth, and Global Xchange, which send teams of volunteers, from two countries, to work and live together, first in one country then in the other (South House Exchange & Canada World Youth 2006; British Council 2007).
Cross-Cultural Contact and Immersion The extent to which the IVS activity creates opportunities for cross-cultural contact may also influence IVS outcomes. Homestays, multinational volunteer groups, and volunteers paired with local workers may increase cross-cultural contact in IVS. Greater cultural immersion may encourage heightened awareness of cultural norms and community needs among volunteers, improve volunteer language development, and provide psychological support to local residents in high-conflict or oppressed areas (VSO 2002). Immersion may lead to ''genuine, fair and respectful reciprocal relations'' that form the foundation for development (Devereux 2006, p. 18). In light of safety and security issues, however, immersion may not always be possible.

IVS Outcomes
This section explores the range and types of outcomes that may result from IVS activities. Figure 1 presents hypothesized outcomes, which may be positive or negative, in host communities, among volunteers, and in sending communities. Although many IVS programs claim that IVS contributes to world peace and wellbeing-and critics point to the dangers of political dependency-we do not address these questions because studies have not attempted to measure global effects. Furthermore, many of the possible relationships among variables are not identified because of a lack of research evidence.
Conclusions about outcomes is based largely on evidence from retrospective, case study, and cross-sectional studies, which capture variation and inform the range of possible outcomes. However, rigorous longitudinal or quasi-experimental designs which permit conclusions about impact are relatively rare. 10 Moreover, the preponderance of research focuses on volunteers. We know far less about outcomes for host communities and sending communities ( Finally, current IVS research also tends to focus on positive outcomes. Despite a widespread assumption that IVS results in a positive net transfer of benefits and resources from sending to host communities (Braham 1999), the transfer may in fact be reciprocal, or possibly one-way in the opposite direction, from host to sending communities (Law 1994;Simpson 2004). IVS may perpetuate, or even accelerate, ''the cultural, political, and economic hegemony of 'First World' over 'Third World' countries'' to the detriment of host communities (Brav et al. 2002, p. 8). As much as possible, the sections below identify positive and negative outcomes.
Host Community Outcomes IVS may affect social, economic, environmental, and political development; host organization capacity; intercultural relations; international understanding; and civic and global engagement in host communities (UNDP 2003).
Social development outcomes potentially include improvements in health, nutrition, education, or welfare services in host communities. Residents may gain language skills (Chelikani and Khan 1990), teaching technologies (Lusk and Rogers 2001), clinical and work skills (Vian et al. 2007b), and social services (Davis Smith et al. 2002;. However, local people may be better able to provide these social benefits, and in some cases, volunteers may gain more than host communities gain on some measures (Rehnstrom 2000).
Economic development includes direct impacts, such as business and market development, as well as spillover effects for local economies from housing, feeding, and sustaining volunteers. Whether these effects bolster local economies depends in part on the direction of resource flows. For example, volunteers could replace or displace local workers and/or volunteers; traditions of mutual aid and self-help could erode; and host communities could become dependent on volunteers (Laleman et al. 2007). It is unclear under what conditions IVS has a positive impact on jobs, poverty reduction, women's lives, or the environment (Rehnstrom 2000). Like traditional development, IVS could be ineffective and even contribute to existing or new inequalities unless programs deliberately address these threats through appropriate training, volunteer selection, sustained joint partnerships and field coordination, and accountability (Lowther and Lucas 1976;Cohn et al. 1981;Brav et al. 2002;Engel 2006;Telford et al. 2006).
Environmentally sustainable development is a focus of many IVS programs, but the results are unclear. While on one hand, IVS could contribute to sustainable development through environmental projects and environmental education, on the other hand, it could contribute to environmental degradation through negative environmental impact on local resources, and increased emissions from increased international air travel (Brook 2007).
Political outcomes may include development resulting from IVS community organizing, advocacy, and human rights and peace work. Interactions between people from different parts of the world through IVS may generate greater understanding and awareness of global inequality and differential power (Devereux 2006). This may result in increased grassroots empowerment and could attract attention of national and international policy makers. In the private sector, companies engaged in social responsibility, including volunteering, might help '''jump start' the development of civil society'' (Logan 2002), although others suggest that the political benefits accrue to sending countries more than host Voluntas (2008) 19:395-421 407 communities (Windmiller 1970). Unskilled international volunteers could expose communities to security or political risks, unless accompanied by sufficient supervision (Dumélie et al. 2006). Furthermore, it is possible that IVS results in greater financial and political dependency for host communities (Brav et al. 2002;Plewes and Stewart 2007). Constructive interaction among people from different countries and cultures may increase intercultural knowledge and skills, and may lead to increased tolerance (CEC 2001;South House Exchange and CWY 2006;Fantini with Tirmizi 2007; that could contribute to community efforts to reduce cultural tensions. Unfortunately, poorly run programs and lack of supervision could result in animosity and tension that casts a shadow on an entire program. An example is criminal acts perpetrated by volunteers while serving abroad (US Department of Justice 2007).
Community leaders and residents may gain greater international understanding and global awareness (South House Exchange and CWY 2006;Sherraden 2007). IVS programs may offer a model of global civic engagement and promote greater international cooperation (ECOTEC 2001;Randel et al. 2004). Host communities may also expand their international social networks, possibly leading to opportunities for social and political development (Woolcock 1998;Spence 2006). Development theory suggests that ''coproduction,'' or the process of using inputs from external actors to create goods or services locally, has the potential to create significant community change (Ostrom 1996). Broader international social networks, for example, could leverage and attract resources and recognition from international donors and others (Comhlámh 2007, p. 8). Personal relationships that emerge from volunteer-community contact may leverage future resources and provide outlets for local goods (Rodrik 1999). Integration into transnational advocacy networks could contribute to local political reforms (Fox 1996). Contact with international social networks could encourage emigration, with a range of potential positive and negative implications (e.g., remittances, family separation, and brain drain) for the host community.
IVS may also affect organizational capacity in IVS host organizations (SOS 1999b;Sherraden and Benítez 2003;Davis Smith et al. 2005;Devereux 2008). On one hand, IVS provides additional staff resources (volunteers) which may increase the quality, efficiency, or volume of services provided by the host organization (Vian et al. 2007b). IVS may also add to cross-cultural skills and knowledge in host organizations. They could expand their relations with the community and their networks of support, including, in some cases, creation of new partner networks (ibid). On the other hand, hosting volunteers can deplete the organization, diverting resources away from service delivery, and disrupt services. Poor selection and training of volunteers could also diminish an organization's capacity to deliver service and potentially threaten its reputation with local residents.

IVS Volunteer Outcomes
There is more research on volunteer outcomes, although most uses cross-sectional or pre-and-post rather than experimental design. Overall, these studies suggest that IVS develops knowledge, skills, and experience that prepare volunteers for living and working in a knowledge-based global economy (ECOTEC 2001;Thomas 2001;Brook et al. 2007). IVS may develop ''higher order'' skills and abilities that contribute to increased capacity to generate income and economic growth (Thomas 2001, p. 7;see also, Grusky 2000;Jones 2004Jones , 2005. These may include technical skills (SOS 1999a;Schröer 2003); language, communication, and problem solving skills (SOS 1999a;CEC 2001;Sherraden and Benítez 2003;Hammer 2005;Moskwiak 2005;Universalia 2005;Brook et al. 2007;Fantini with Tirmizi 2007;Kelly and Case 2007), and leadership, organizational, human relations, and team building skills (Grusky 2000;Thomas 2001;de Gilder et al. 2005;Jones 2005;Vian et al. 2007b).
Developing critical thinking skills may be accelerated during IVS ''due to the ways in which culture, language, religion, and beliefs are under constant challenge in foreign settings'' (Kraft 2002, p. 308; see also Brook et al. 2007). Moreover, learning may occur quickly and seem relatively effortless because ''it is centered on practical activities and everyday life experiences'' (Mutz and Schwimmbeck 2005, p. 60).
IVS may contribute to employability, including helping volunteers qualify for more lucrative and interesting international positions in private and public sectors (Jones 2004;Moskwiak 2005;Mitka 2006;Schulz and Kelly 2007), although longer term volunteering may be necessary . IVS also provides opportunities to broaden horizons and explore career directions (Bell 1994;. Some employers, who sponsor international service among employees, believe that IVS develops confidence, breadth of experience, and ability to embrace diversity on the job (Cook and Jackson 2006). Other employers may not recognize the human capital skills gained in an international volunteering experience (Thomas 2001;Davis Smith et al. 2002;Brook et al. 2007), and some may not know how to benefit from employees' new skills (Vian et al. 2007b). At the same time, IVS potentially puts employees out of touch, interrupting their education and employment, and interfering with promotions and other advancement opportunities (Rolles 1999;Cook and Jackson 2006).
IVS may contribute to personal and human development through heightened maturity, self-confidence, self-efficacy, self-awareness, and independence (Cross 1998;SOS 1999a;Wilson 2000;CEC 2001;Thomas 2001;Unterhalter et al. 2000;Schröer 2003;Cook and Jackson 2006;Poole and Davis 2006;Brook et al. 2007;Schulz and Kelly 2007). It may offer an important ''psycho-social moratorium,'' encouraging reflection and personal growth (Stein 1966, p. 238). Some suggest that IVS replaces traditional rites of passage . Often, volunteers are living outside of their country and culture for the first time, possibly learning another language, interacting with people who are different from themselves, and engaging in demanding, rewarding, and fulfilling work. The potential is high, therefore, for IVS to be a transformative experience in the lives of volunteers (Starr 1994;Grusky 2000;Hudson and Inkson 2006;Fantini with Tirmizi 2007).
IVS volunteers benefit in different ways. For example, some research suggests that IVS offers particular benefit to the economically and otherwise disadvantaged (Adams et al. 1996;EVS 1999;Stopforth 2001;AVSO 2001AVSO , 2004Spring et al. 2007). According to a study of domestic volunteering, disadvantaged volunteers may develop greater self-reliance and autonomy, and disassociate themselves from negative labels and stereotypes because of the new experience, although this experience may differ in IVS (Davis Smith et al. 2005). The same may hold for international volunteers.
Exposure to and interaction with people who are different may increase mutual understanding (Zimmerman 1995), and lead to intercultural competence, considered essential for full participation in contemporary society. International volunteers may develop greater open-mindedness (South House Exchange and CWY 2006). Intercultural competency includes knowledge and skills that enable people ''to perform effectively and appropriately when interacting with others who are linguistically and culturally different'' from themselves (Fantini with Tirmizi 2007, p. 5; see also Gillert 2000). Intercultural competence may be cultivated when IVS programs emphasize it (CEC 2001;ECOTEC 2001;McBride et al. 2003;Schröer 2003;Sherraden and Benítez 2003;Hammer 2005;Universalia 2005;Fantini with Tirmizi 2007;). Developing intercultural competence may result especially when volunteers and community residents have equal status, shared goals, and sanctioned activities (Allport 1954). In this way, some forms of international volunteering may result in greater awareness and tolerance, lessen prejudice and ethnocentrism (Pitner 2007), and perhaps even celebration of cultural differences.
In contrast, some forms of IVS could contribute to views of the third world as ''binaries of us and them,'' even reinforcing stereotypes that IVS programs are more akin to tourism than service (Simpson 2004, p. 690; see also Brav et al. 2002). ''Fluent fools,'' as Gudykunst (1998, p. 3) has labeled some, may learn a new language but gain little knowledge and understanding of different cultures.
IVS may also result in greater knowledge and understanding of social, economic, and political issues in global context (Hayward and Siaya 2001). For instance, volunteers report better understanding of other countries, minority issues, immigration, and inequality (Law 1994;Grusky 2000;South House Exchange and CWY 2006;Sherraden 2007), and an enhanced global perspective (Purvis 1993). Global understanding from an IVS experience may also help transform volunteers into ''citizens of the world,'' in the ethical sense, who feel a shared identity with others outside of their own country (Nussbaum 1997, pp. 50-84; see also Dower and Williams 2002;Sherraden and Benítez 2003), and may contribute to national security (Rieffel and Zalud 2006), although some studies suggest this shared identity may be superficial .
Finally, volunteers may engage in civic learning that instills civic values and skills, and encourages future civic engagement (EVS 2001;Davis Smith et al. 2002;Mutz and Schwimmbeck 2005;Rehberg 2005;Rockliffe 2005). It may also promote a heightened sense of responsibility for improving the common good worldwide (Williams 1991;Purvis 1993;SOS 1999a;Sherraden 2001Sherraden , 2007Jones 2005;Universalia 2005;Fantini with Tirmizi 2007;Machin 2008). Volunteers may find greater involvement enriching, but also may benefit personally from international social networks with global contacts for future employment and global influence. Some research on short (two-week) workcamps finds that civic attitudes are not improved, which suggests that such changes may require more time ).

Sending Community Outcomes
Large numbers of returning volunteers may also affect sending communities and countries. Nonetheless, relatively few studies measure possible outcomes regarding human capital, cross-cultural interaction and conflict resolution, development, global civic engagement, and public policy in sending communities (Machin 2008).
As a group, returned IVS volunteers could contribute to aggregate increases in human capital, and lower levels of risk behavior and social exclusion, in sending countries (ECOTEC 2000), possibly leading to economic and social development. For example, one study found higher rates of teacher retention after lengthy period of service abroad (Unterhalter et al. 2002). Volunteering abroad may, like domestic volunteering, lead to future volunteering at home (Manitsas 2000;de Gilder et al. 2005;Rockliffe 2005;Universalia 2005;VSO 2006a). Public officials in Singapore, for example, deliberately pursue IVS to develop civic society, a sense of inclusion, domestic volunteerism, and national pride and identity, in this case ''self development'' by government (Krishna and Khondker 2004, p. 32).
On the downside, sending communities may have to generate replacements and extra resources to cover people during the time they are volunteering abroad (Thomas 2001;Cook and Jackson 2006;Hutchings and Smart 2007). Further, IVS could contribute to returned volunteer physical mobility, fueling internal migration or emigration.
Returned IVS volunteers could improve cross-cultural relations or resolve social conflicts at home. They may bring a more nuanced understanding and broader perspective of global issues and development (Fuchs 1967;Hutchings and Smart 2007). Moreover, they could help to dispel myths about foreigners, spark dialogue about disadvantaged populations, explain the importance of local and global interdependence, and encourage global action by others (VSO 2006b).
Global awareness among returning volunteers and sending organizations could enhance capacity to solve local, domestic, and international conflicts, and encourage support for development aid (Universalia 2005;Plewes and Stuart 2007). Large numbers of people engaging in IVS could increase access to global networks for their own communities and countries. With these ideas in mind, some IVS programs promote continued involvement in global advocacy, such as the ''Make Poverty History'' campaign (Devereux 2006).
IVS sending organizations may also benefit from added cross-cultural expertise, expanded organizational reach, more information, and improved status and reputation (SOS 2000;CEC 2001;de Gilder et al. 2005;Davis Smith et al. 2005). Although some organizational constituents may not support IVS efforts and believe that resources should be invested at home (de Gilder et al. 2005), there also may be positive feedback effects that lead to more support and advocacy for IVS policies and programs. Voluntas (2008) 19:395-421 411 Future Research: Toward Understanding the Impact of IVS A limitation of the conceptual model proposed in this paper is that it relies primarily on studies published in English and therefore generalizability may be limited to the contexts where these programs take place. Evidence from studies in other languages is an important next step. Tapping experiences of IVS in different contexts could support or challenge the empirical data and conceptual relationships proposed in this paper. Further, the majority of studies assess positive benefits of IVS, with less evidence presented on drawbacks and negative implications for host and sending communities and volunteers. Overwhelmingly positive results likely reflect the predominance of research that focuses on volunteers, especially those who complete a term of service, who tend to assess service in a positive way. More research from IVS program exiters and from host community perspectives may challenge existing findings, or at least provide greater balance. Moreover, bias toward positive findings suggests that researchers should develop methods of inquiry that will capture a wider range of potential outcomes and help to build knowledge.
Although this survey of research suggests there is a critical mass of descriptive information about IVS, including its various forms, the institutional context, and intended outcomes, there is, as Virginia Hodgkinson suggests, ''much rhetoric but little hard research and data to support civic service as important to citizenship (national or in other groups) or its impact on public benefit (whether to community, nation, region, or world)'' (2004, p. 192S). We lack understanding about how and why particular forms of IVS and different contexts lead to different outcomes (Machin 2008). It is important to know, for example, if some forms of IVS lead to deeper mutual understanding while other forms lead to superficial and stereotypical views of the other. Further, research should examine relationships among outcomes. It is possible for example, that increased self-awareness among volunteers increases positive outcomes for the host community (Devereux 2006).
In order to build an evidence base, the field must adopt common terminology and definitions, research questions driven by theory, and rigorous research designs, data collection methods, and instruments that allow for comparison and the counterfactual. As for terminology, the very definition of who is an ''international volunteer'' is contested (Carson 1999;UNV 1999;Dingle et al. 2001;Merrill 2006;Devereux 2008). While uniformity would promote comparability, it may not be realistic at this stage due to perceived differences in voluntary action worldwide . However, we can aim for transparency in how we conceptualize and measure international volunteering and service. Beyond the actual act itself, there is a range of characteristics that are likely to have impacts, from volunteer capacity to institutional capacity in sending and host countries. Theory should inform which characteristics we measure.
Formal theory is largely absent from existing research on IVS, but ask practitioners and they will give you their theory of change and ideas about how and why the program affects community members and volunteers. It is important to articulate these ideas and develop testable research questions and hypotheses. Gordon Allport's (1954) intergroup contact theory, Milton Bennett's (1993) developmental model of intercultural sensitivity, and Jack Mezirow's (1996) transformative learning theory, are examples of formal theories that may help specify why certain variables are expected to lead to predicted outcomes for volunteers. Based on our knowledge of the field and a review of existing research, we believe that the most productive questions address impacts across the four primary stakeholder groups, including sending organizations, volunteers, host organizations, and community residents. Use of theory will also help to offset a positive bias evident in much research on IVS.
The tools of social science research already assist the field with development and implementation. For example, needs assessments and capacity assessments inform policy and program design, directing volunteer efforts to areas of greatest hardship. Implementation assessments by IVS programs track volunteer activities, community resident involvement, and stakeholder satisfaction. These methods help to lay a foundation for effective programs, but they also form the knowledge base required for impact assessments. We cannot know the impact of an IVS policy or program unless we understand the volunteering context and volunteer actions. This requires systematic data collection involving all stakeholders, including volunteers, supervisors, host organizations, community members, and sending organizations (IVR 2004).
Regarding research methods, the overwhelming majority of research is based on case and cross-sectional studies . While these have contributed enormously to what we know about the field, they do not permit us to draw conclusions about the impact of IVS. Impact assessments require comparative designs that permit researchers to compare the target of change (an individual, organization, or community) with a similar target, but one that does not have an IVS program. Rigorous research also requires a pre-test/post-test design and standardized impact measures. The quality of research findings will be contingent on rigorous research instruments. A number of volunteer measurement toolkits have been developed that inform participatory appraisals and program evaluation, although in order to build a comparative evidence base, standardized instruments implemented across IVS programs and contexts are needed (Dingle et al. 2001;IVR 2004;Daniel et al. 2006).
To be sure, the kind of rigorous research discussed here is costly, but so are ineffectual policies and programs. The field will benefit from investment in organizational infrastructure to collect impact data, as well as investment in researchers to conduct projects across IVS forms and ideally, across countries. It is also important that we look for and report negative and/or neutral results and introduce methodological controls on respondent and researcher bias. For IVS to achieve scale and become as effective as possible, a few key impact studies would advance knowledge greatly.

Conclusion
Research has not kept pace with the growth of international volunteering and service as an emergent international institution (Davis Smith and Ellis Paine 2007;). Does IVS make unique and positive contributions to host communities, Voluntas (2008) 19:395-421 413 volunteers, and sending communities? IVS may lead to greater cross-cultural competence, including language and communication skills; greater international understanding; enhanced ability to solve conflicts; widespread and democratic participation in global affairs through global civic society organizations; and growth of international social networks among ordinary people. IVS may lead to improved international understanding and cooperation across borders. In contrast to models of traditional development that rely on professional technical assistance, IVS volunteers may engage in communities in ways that develop relationships, interpersonal trust, and understanding that lead to capacity development at the grassroots and provide an alternative to traditional development strategies (Devereux 2006(Devereux , 2008; see also Lewis 2005). In these scenarios, benefits could accrue to host and sending communities, and volunteers, and contribute to the global greater good. In contrast, IVS may do little to improve global relations if it reproduces or reinforces existing inequalities, creates dependency and a ''new form of colonialism,'' contributes to elitism, or advances state interests over host community goals (Mohan and Stokke 2000;Siekmeier 2000;VSO 2006b). A paternalistic model in which IVS is limited to volunteers of means from wealthier areas of the world may offer privileged volunteers an international perspective and a career boost, but it does little for people who currently lack access to an IVS experience. It also is likely to do little for host communities. Those who volunteer will continue to reap the benefits of IVS, using host organizations and host communities as a rung on the ladder of personal advancement, without making lasting contributions and providing avenues for advancement to those who are ''served.'' In this scenario, benefits accrue in a lopsided fashion, providing greater advantage to volunteers and sending communities than to host communities, contributing to the status quo in global relations instead of providing opportunity in both directions and developing international understanding and cooperation across borders.
The conceptual model presented here provides an initial framework for future studies that explore these possibilities. However, building evidence about the contributions of IVS will not be simple. There is wide variance across IVS programs, volunteers, and community contexts. Identifying impacts and generalizing findings beyond individual IVS programs will be challenging. This paper identifies significant gaps in knowledge and recommends a rigorous and comprehensive research agenda on IVS. More research that is rigorous will not only contribute to a better understanding of an emergent international phenomenon, but also is important for effective practice and policy.