We explain the role of the Phillips Curve in the analysis of the economic outlook and the formulation of monetary policy at the ECB. First, revisiting the structural Phillips Curve, we highlight the challenges in recovering structural parameters from reduced-form estimates and relate the reduced-form Phillips Curve to the (semi-)structural models used at the ECB. Second, we identify the slope of the structural Phillips Curve by exploiting cross-country variation and by using high-frequency monetary policy surprises as instruments. Third, we present reduced-form evidence, focusing on the relation between slack and inflation and the role of inflation expectations. In relation to the recent weakness of inflation, we discuss the role of firm profits in the pass-through from wages to prices and the contribution of external factors. Overall, the available evidence supports the view that the absorption of slack and a firm anchoring of inflation expectations remain central to successful inflation stabilisation.