Abstract: At the Copenhagen summit of 1993, the European Union introduced three criteria for accession to the European Union-political, economic, and adoption of the acquis-combined in 1995 with the necessity, for the candidate states, to have the institutional capacity to implement the acquis. Until the reform of the PHARE programme in 1997, the European Union did not have any cooperation programme for institution-building. Conceived as an innovative instrument in European external cooperation, institutional twinnings are inspired, in their design and their implementation, by new methods of governance emerging from the internal policies of the European Union (new public management, open method of coordination). How did the candidate countries interpret and implement institutional twinnings? Can one simply speak of institutional transfers or are the results of cooperation between Western and Eastern elites and experts of a more complex nature? This article attempts to draw some lessons from the experience of twinning on the basis of sectoral case studies in two countries, Estonia and Hungary, which took part to the EU enlargement of May 2004.