The ultimate litmus test of compliance theories occurs in situations where states' interests are directly opposed, such as competing interstate claims over territory, maritime areas, and cross-border rivers. This article considers the extent to which the involvement of international institutions in the settlement of contentious issues between states bolsters compliance with agreements that are struck. Institutions may influence the prospects for compliance actively and passively. Active institutional involvement in the conflict management process increases the chances for compliance with agreements, particularly for binding institutional activities, relative to the active involvement of noninstitutional third parties. More passively, joint membership in peace-promoting institutions enhances the likelihood that states will comply with peaceful agreements to resolve contentious issues. Empirical analyses demonstrate the relevance of international institutions for resolving contentious interstate issues both actively and passively, although the results suggest that institutions are more effective conflict managers when they choose binding settlement techniques.