Background: Multistakeholder alliances that bring together diverse organizations to work on health-related issues are playing an increasingly prominent role in the U.S. health care system. Prior research shows that collaborative decision-making and effective leadership are related to members' perceptions of value for their participation in alliances. Yet, we know little about how collaborative decision-making and leadership might matter over time in multistakeholder alliances. Purpose: The aim of this study was to advance understanding of the role of collaborative decision-making and leadership in individuals' assessments of the benefits and costs of their participation in multistakeholder alliances over time. Methods: We draw on data collected from three rounds of surveys of alliance members (2007-2012) who participated in the Robert Wood Johnson Foundation's Aligning Forces for Quality program. Findings: Results from regression analyses indicate that individuals' perceptions of value for their participation in alliances shift over time: Perceived value is higher with collaborative decision-making when alliances are first formed and higher with more effective leadership as time passes after alliance formation. Practice Implications: Leaders of multistakeholder alliances may need to vary their behavior over time, shifting their emphasis from inclusive decision-making to task achievement.