This article examines the institutionalization of policy evaluation in Belgium. In comparison to other western democracies, policy evaluation is an underdeveloped tool of Belgian public governance. Among the explanatory factors of the laggard situation of Belgium, we focus on the all-pervasive phenomenon of partitocracy, on the relative weakness of Parliament vis-à-vis the government, and on the federalization process that is characteristic of the recent institutional evolution of the country. These three peculiarities of the Belgian polity and politics jeopardize the development of a mature evaluation culture. Finally, the empirical evidence for the Belgian case also calls into question several of the theoretical hypotheses that have been formulated to explain the diffusion of policy evaluation in various democracies.