The present paper tests the effects of governance structure on organizational performance. While most studies in public management are concerned with the impact of different types of managerial behavior on organizational performance, the context of the governance structure is mostly neglected. The Dutch institutional context is distinctly different from the U.S. context and characterized by schools clustered in boards with specific governance characteristics: legal form, denomination, multiplicity, and size. We propose that school boards’ governance structures have a contingent impact on school performance, affecting the way(s) that managerial activities of school principals affect school performance. We hypothesize that (1) school performance significantly varies at the school-board level; (2) school board complexity negatively affects school performance; (3) school board governance structure significantly affects the level of principals’ managerial activity, but (4) in different ways for different dimensions of managerial activity; (5) School principals’ managerial activities have different effects on school performance for schools residing under different governance structures. We test our hypotheses on a nested dataset that includes (a) measures for different dimensions of school principals’ managerial networking and human capital, scope of internally oriented management activities, and (b) measures tapping the governance structure of the school boards in which the schools are nested. These data are combined with data on school pupils’ scores on standardized tests, as well as a wide range of control variables that capture school, staff, and pupil characteristics (N = 422). Regression analyses show partial support for our hypotheses. Indeed, governance structure affects managerial behavior but does not (co-)determine the transformation of managerial behavior into school performance.