ABSTRACT. For programs that aim to promote forest conservation and poverty alleviation, such as Reducing Emissions from Deforestation and Forest Degradation (REDD+), the participation of indigenous communities is essential to meet program goals. Using Ostrom's theory of collective action for common pool resource management, we evaluated the institutions governing indigenous participation in the Programa Socio Bosque incentive-based conservation program in Ecuador. We conducted structured interviews with 94 members in 4 communities to assess community institutions for 6 of Ostrom's principles, using 12 measures we developed for the principles. We found substantial variation between communities in terms of their institutional performance. The best-performing community performed well (>50% of interviewees reported successfully meeting the measure) on 8 of the 12 measures. The weakest performed well on only 2 out of 12 measures. Overall, our results indicate that there is stronger performance for constitutional-levelinstitutions, which determine who gets to make the rules, and some collective-choice institutions, which determine how local rules are made. We identified specific challenges with the day-to-day operational institutions that arise from participation in nation state–community conservation programs, such as restricted resource appropriation, monitoring and compliance, and conflict resolution. We found that top-down policy making has an important role to play in supporting communities to establish constitutional-level and some collective-choice institutions. However, developing operational institutions may take more time and depend on local families’ day-today use of resources, and thus may require a more nuanced policy approach. As some countries and donors find a jurisdictional REDD+ approach increasingly attractive, complementing top-down policy measures with bottom-up institutional development could provide a stronger platform to achieve the shift from current land use driving deforestation to a lower-carbon-emissions land management trajectory.