This three-paper dissertation aims to evaluate whether, how, and the extent to which immigrants' volunteering affects their integration into the host country. I approach the thesis with a conceptual examination built on social theories (Paper 1), a quantitative analysis conducted with Canadian data (Paper 2), and a qualitative exploration based on 24 interviews conducted in Philadelphia (U.S.) (Paper 3). For Paper 1, I find that while existing social theories may explain ways volunteer activities positively influence the relationship between immigrants and nonimmigrants, they do not account for additional barriers newcomers experience during resettlement. Using an intersectional approach, I expand existing knowledge on immigrant-nonimmigrant relations by exploring volunteering as support that improves immigrant integration. In Paper 2, I use Canadian national survey data to examine three dimensions of immigrant integration: professional, psychosocial, and political. General volunteering is not significantly related to integration; however, there is a relationship between dimensions of integration and where immigrants choose to volunteer. Thus, the relationship between immigrant integration and volunteering is nuanced; it matters where immigrants decide to volunteer. I expand on this in Paper 3 by analyzing 24 semi-structured interviews to explore differences in social-integration experiences and perceptions of social integration between immigrant volunteers and nonvolunteers in Philadelphia. While past studies assert that volunteering increases feelings of social integration, this empirical study offers a comparative perspective between immigrants who volunteer and those who do not. The findings suggest that immigrant volunteers build a stronger sense of agency in their social integration journeys through contributions to society. Most nonvolunteering participants achieve similar yet minor benefits by engaging in informal volunteering outside of organizational auspices. This dissertation inspires recommendations for researchers, policymakers, and practitioners working towards improved immigrant integration. Voluntary venues are unique for positive relational dynamics between immigrants and nonimmigrants. More research on the integrative qualities of voluntary work may lead to discovering best practices on how immigrants achieve high levels of integration within communities and beyond.