The proper distribution of powers between the supranational institutions and the member states of the European Union is the object of many academic and public debates. By examining the distribution of powers between the Commission and national administrations in the implementation of EU law, Fabio Franchino makes a valuable contribution to these discussions. His book investigates why and to what extent the EU’s legislative institutions delegate implementation tasks to either the Commission or the national administrations. Furthermore, given the delegation of an implementation task to one of these actors, the book asks how much discretion the actor is given to fulfil its tasks and what the underlying reasons are for the legislative institutions to grant more or less leeway to the implementing actor.