Taking Bulgaria as an example, this article examines how the EU accession process transforms a key policy area – the environmental sector. Starting with a disastrous legacy and very weak institutions ten years ago, Bulgaria’s environmental policies have been dramatically transformed in the decade preceding the country’s EU accession in 2007. Although a number of the problems have not been (fully) overcome yet, Bulgaria now has the institutions and policy tools in place to address the remaining challenges. This stands in stark contrast to the situation in 1997 and illustrates what a powerful reform motor the EU accession process is.