Parliaments’ engagement in post-legislative scrutiny can be considered either as an extension of the legislative function or within the framework of the oversight of the executive. This article makes use of the latter view to assess how parliaments in Europe approach post-legislative scrutiny and to which extent this function can be regarded as a form of executive oversight. Although rules and practices of parliaments in this realm are remarkably heterogeneous, the focus on some selected parliaments (Italy, France, Germany, Sweden, and the European Parliament) reveals three different conceptual categories. In the ‘basic’ approach (passive scrutinizers), parliaments limit their role solely to the assessment of the ex-post scrutiny performed by the government and external agencies. Differently, parliaments willing to engage in a more proactive approach might choose either to act on an informal basis, establishing ad hoc research/evaluation administrative units (informal scrutinizers) or to address post-legislative scrutiny in a formal and highly institutionalized manner (formal scrutinizers). As a matter of fact, the practise of parliaments often combines characters of different categories. While in all of these approaches post-legislative scrutiny shows potential for executive oversight, only the third can potentially lead to a kind of ‘hard’ oversight.