A specific form of corporate social responsibility—corporate philanthropy—has received little attention in sport scholarship despite the increased formalization of this business function in practice. Specifically, few studies have explored the institutional mechanisms that influence the corporate philanthropy of professional sport teams. Given that teams receive simultaneous institutional pressures from their league and from the community in which they operate, this study examined how the presence of multiple peers from different fields affected teams in terms of determining the appropriate level of philanthropic activity. The hypotheses were tested through a longitudinal analysis of philanthropic data from team foundations in four professional leagues in the United States from 2005 to 2017. The authors found that teams were more likely to be affected by the philanthropic giving levels of league peers than local peers. Overall, this study provides a better understanding of simultaneous institutional pressures shaping the philanthropic activities of professional sport teams.