This article investigates the determinants of nonprofits' involvement in cogovernance, or the planning and design of public services, using a unique data set of park-supporting nonprofit organizations in large U.S. cities. The results indicate that nonprofits are more likely to get involved in cogovernance when they are younger, larger, and operate in communities that are more resourceful and stable. In addition, the likelihood of nonprofits' involvement in cogovernance is negatively associated with the level of social capital and government capacity to provide corresponding public services. The article points to an emerging mode of government-nonprofit collaboration that goes beyond the production and delivery of public services. As public managers face extensive challenges in sustaining the desired level of public services, these findings have important policy implications for efforts to promote citizen participation and cross-sector solutions to complex social problems.