There is an increased awareness that the performance of boards (good governance) is not only determined by structural determinants but by behavioral determinants as well. These behavioral determinants might be particularly important for public and nonprofit governance, where the role of the board is more diffuse and heterogeneous than in corporate governance. Here we investigate how social dynamics within boards in secondary education influence their performance. We follow a concise model that includes cognitive conflict, the use of expertise, effort norms, and social cohesion as determinants of board task performance. A survey among all secondary schools in the Netherlands serves as the empirical underpinning for this process‐oriented model of good governance. We show that the behavioral determinants have different effects on the control task and advice task of boards. Also, we find that cognitive conflicts in supervisory boards do not lead to less but rather to more social cohesion within boards. Building on these findings, we suggest a revised model of the behavioral determinants of nonprofit board performance.