This chapter builds on recent OECD work, to offer some general considerations on the application, success and challenges of ex post evaluation of regulations by governments. The chapter provides some reflective thinking on a number of issues to inform the refinement of the governance underpinning the design, implementation and management of ex post evaluation and the related reforms. There are two potential tensions that may emerge when organising and carrying out ex post evaluations. The first tension spans along the centralisation – de-centralisation – outsourcing spectrum. This requires properly organising the plurality of the channels, of the actors and of their “entry points” that form the evaluation regime. A second tension may by reflected by the trade-off between quantity and quality – i.e. between the number of the evaluations and their relevance to decision-making in terms of comprehensiveness (depth), timing, and hence usefulness and of the analysis.