This chapter reviews the European Union’s (EU) policy mechanisms under the European Neighbourhood Policy (ENP). It seeks to explore the processes through which ENP decisions are adopted and implemented in countries on which the EU cannot hierarchically impose its own rules. It focuses on those mechanisms through which the EU has diffused its norms and influenced domestic change in the neighbourhood, namely conditionality, socialisation and differentiation. In doing so, the chapter investigates how the mechanisms adapted from enlargement policy have evolved since the ENP was launched, the extent to which they have proved effective in transforming the EU’s eastern and southern neighbourhoods and how they have been reassessed to respond to a changing political landscape in both ‘neighbourhoods’.