Book excerpt: This volume focuses attention on key environmental and institutional changes associated with eastern expansion of the European Union, assessing and challenging prevailing views about the outcomes and processes of this historic development. Looking at four central themes -- capacity changes and limitations, the EU's mixed messages and conflicting priorities, non-state actor roles and developments, and the exchange of ideas and information - the volume shows that enlargement will change the EU, not just make it bigger, and that EU officials and programs are improving aspects of environmental policy in CEE countries even as they are making others less sustainable. This book was previously published as a special issue of the journal Environmental Politics.