Enlargement and the Environment: The Changing Behaviour of the European Parliament* CHARLOTTE BURNS 1 , NEIL CARTER 2 and NICHOLAS WORSFOLD 3 1 University of Leeds. 2 University of York. 3 University of York Abstract It was widely anticipated before European Union enlargement that the accession states would have a negative impact on EU environmental governance. By extension, the European Parliament’s (EP) reputation as an environmental champion might be threatened by the influx of MEPs from accession states. An analysis of all EP amendments to environmental legislation between 1999 and 2009 reveals that post-enlargement the EP was more successful at securing the adoption of its amendments into law but that these amendments were less radical. These changes arise from the institutional adaptation prompted by enlargement and a broad ideological shift to the right within the EP. Introduction Prior to the enlargement of the European Union (EU) in 2004 several observers predicted that its expansion from 15 to 25, and then to 27, Member States would seriously impair the quality of EU environmental governance (for example, Holzinger and Knoepfel, 2000). The new Member States (NMS) were significantly poorer and less economically developed than most existing Member States and they already faced the costly burden of implementing the environmental acquis communautaire of several hundred pieces of legislation. Conse- quently, it was anticipated that their politicians would resist the introduction of further progressive EU environmental legislation (Homeyer et al., 2000; Wilkinson et al., 2004). Enlargement would result in an influx of new MEPs who might weaken the reputation of the European Parliament (EP) as a strong advocate of environmental concerns (Schreurs, 2004). Similarly, a tranche of ministers from the NMS would shift the balance of power within the Council of Ministers away from environmental ‘leader’ states in favour of those ‘laggard’ states that resisted extending environmental regulation (Holzinger and Knoepfel, 2000; Schreurs, 2004). Thus enlargement posed a serious potential threat to the continua- tion of the EU’s role as a progressive environmental actor. This article assesses the impact of enlargement on EU environmental governance by examining whether it has affected the way the EP treats environmental legislation. It draws primarily on a data set that categorizes 7,065 amendments adopted by the EP to 112 pieces of environmental legislation over a ten-year period from 1999 to 2009. Each amendment is classified according to its environmental importance and the extent to which it was incorporated into the final legislative text. This rich and comprehensive * This article is based on research funded by the Economic and Social Research Council, Project Research Number RES-000-22-2304. The authors would like to thank JoAnn Carmin, Simon Lightfoot and Tony Zito for their helpful comments on an earlier draft. JCMS 2012 Volume 50. Number 1. pp. 54–70 DOI: 10.1111/j.1468-5965.2011.02212.x © 2011 The Author(s) JCMS: Journal of Common Market Studies © 2011 Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA