The study deals with the impact of the European Neighbourhood Policy (ENP) on political regimes dynamics in Eastern Partnership countries in the period 2007 to 2013. Based on the regime transition theory, Europeanisation perspective and political economy, the research claims to introduce a new theoretical model which allows to combine domestic and international factors of regime dynamics. By using the rational choice institutionalism as an analytical framework, and employing the multi-value qualitative comparative analysis (mvQCA) in combination with case studies of Georgia, Moldova and Ukraine it shows that the ENP could lead to three different outcomes: democratization, stabilization of a hybrid regime, and authoritarian consolidation. The outcomes are explained by the fact that the assistance within the ENP is used by ruling elites for implementation of two conflicting strategies: the strategy of partial political reform equilibrium preservation and the strategy of new political reform equilibrium formation. Variation in the ENP's influence on the dynamics of a particular political regime is dependent on the predominance of one of these strategies, which in turn are mediated by three main domestic factors: the type of political system, the level of political monopolism, and the degree of government effectiveness. The article contains three parts. The first part presents a brief review of the main theoretical approaches to the analysis of political regimes dynamics. A general analytical framework is formulated. The second part shows how the ENP influenced the dynamics of political regimes in Eastern Partnership countries. The third and final part demonstrates the logic of such influence by examples of Georgia, Moldova and Ukraine.