While considerable consensus exists regarding the importance of internationalizing postsecondary education, little is known about whether distinct forms of internationalization influence civic engagement. This study estimates the degree to which study abroad and internationalization at home (IaH) are associated with international volunteerism among undergraduate alumni at research universities in the United States (n = 93). Results from a multiple regression analysis revealed that extensive IaH--reflected by both the presence of internationalized general education and a high concentration of international students--and the institutional study abroad rate were both positively associated with international volunteerism, operationalized as participation in the Peace Corps. Limited forms of IaH were not predictive of international volunteerism. Regression models explained between 29 and 38% of the variance in international volunteerism. The findings suggest that institutions can better prepare students for the challenges of global civic engagement by increasing participation in study abroad and implementing an extensive and systematic IaH strategy.