The aim of this article is twofold. First, I review the political science literature on delegation and control and apply the control side of agency theory to the activities of the Commission. Second, I test McCubbins and Pages (1987) propositions on the determinants of control. I then conclude with some comments on the impact of these procedures on Commissions autonomy, with reference to other works on the subject. Hypothesis: McCubbins and Page suggest that the stringency of ex post control is positively correlated with 1) conflict among legislators and 2) uncertainty about the benefits and costs of the policy. Methods: I use logistic regression and a cumulative logit model that test the hypotheses on a stratified sample of non amending secondary legislation adopted from 1987 to 1998. Results: Unanimity rule, conflict between Community institutions and uncertainty about the costs and benefits are key determinants for the establishment of ex post procedural control of Commissions implementation activities. Conflict and uncertainty are also important factors affecting the degree of stringency in control.