The central questions of this article are when, how and what do governmental agencies learn from evaluations. A structural constructivist theoretical framework is developed and applied to two case studies, both of which take a report by the Dutch Court of Audit (CoA) as a starting point. A reconstruction is made of the intra- and interorganizational processes through which the impacts of these evaluations were socially constructed. It appears that an evaluation has hardly any direct effect that can be unequivocally ascribed to it. Rather, evaluations seem to support or counteract debates, tendencies and options already present (or 'under construction') in the interaction among the actors involved. Using a structural constructivist theoretical framework we identify mechanisms and conditions that enhance forms of learning processes.This article concludes with some hypotheses about the genesis of evaluation impact.