Impact assessment (IA) has gone from an innocuous technical tool typically used in the pre-legislative phase to an instrument at the heart of the European institutional machinery. However—in deviation from its roots as a tool governing delegated rulemaking in the US—most experience with IA in the EU has been gathered in a legislative context. Against the background of the recent evolution of the EU's old ‘comitology’ system into a two-track system of delegated acts and implementing measures, this contribution discusses in three parts the ‘whys,’ ‘whats’ and ‘hows’ of extending IA to ‘non-legislative rulemaking.’ It explores various aspects of the rulemaking process that IA—if properly applied—could strengthen: consultation, control and quality.