Many experts and practitioners expected the 2004 enlargement to affect both the efficiency and content of policy-making in the EU. In contrast to these expectations, most accounts of decision-making in the Council of Ministers following May 2004 have concluded that the effect has been only moderate. The EU’s most important legislative body is commonly found to function relatively smoothly following the enlargement big bang in 2004. Yet many aspects of the enlargement of the EU institutions have still not been adequately reported or evaluated. In order to give a more nuanced insight into the impact of enlargement, this policy brief presents and analyses data revealing some of the general changes that have occurred in the Council since May 2004. The analysis shows that this institution has indeed been challenged by the difficult task of getting 25 member states to come to agreement. One can then only wonder what the consequences are of an EU of 27. Furthermore, although the findings do not appear to reflect any immediate crisis in terms of the overall efficiency of the institution, the evidence is mixed with regard to how individual policy areas have been affected. Lastly, the data indicate that the internal work processes in the Council have been influenced by the expansion. Each of these observed changes may in the long run have important implications for the nature and content of policy-making in the EU, and pose further challenges to the transparency of the institution and accountability of the government representatives.