Many studies suggest that conditionality is a more effective democracy promotion strategy (DPS) than incentives. This paper confirms the validity of this hypothesis by demonstrating that conditional pre-accession political reforms, required from the eastern and central European applicants by the European Union, have substantially progressed from 1998, while the impact of incentives democratic aid programmes carried out by donors since l994 has proved to be either very modest or non-existent. Then it explains these unequal performances by synthesizing insights provided by the analysis of both DPS processes of implementation, interviews conducted with the European Union Eastern Enlargement negotiators and literature devoted to democratic aid programmes, international co-operation and compliance of states with international institutions norms and rules. On the whole, the study challenges the endogeneous theory of comparative politics according to which 'democracy is a domestic affair par excellence'.