This article suggests that the literature on how the European Union (EU) diffuses its norms externally and that on how it diffuses them internally should be linked. Therefore, the focus is on a field where the EU is described as a ‘normative’ power: climate change. The article analyzes how EU climate norms are diffused to new Member States. It argues that there are two roads to state socialization: through civil servants participating in EU work, and via domestic norm entrepreneurs. The empirical analysis is based on how four of the Member States that joined the EU in 2004–07 worked with the Climate and Energy Package of 2008–09. With the exception of one of the countries, there are few indications of an ongoing socialization process among them. For the EU as a normative power it is important to reflect upon why the underlying EU climate norms are rejected in the studied countries.