Frank Schimmelfennig is a Fellow of the Mannheim Center for European Social Research, Germany.

'… the book provides valuable information for people interested in two major theories of international relations in practice. … Schimmelfennig gives a deep insight in the process and the outcomes of NATO and EU enlargement as such and develops a theoretical approach that seems applicable to future Western organizations' enlargement decisions.' Steve Schwarzer, European Societies

• List of figures; List of tables; Acknowledgements; List of abbreviations; Introduction; Part I. Security, Power or Welfare? Eastern Enlargement in a Rationalist Perspective: 1. Rationalist institutionalism and the enlargement of regional organizations; 2. NATO enlargement; 3. EU enlargement; Conclusion: the rationalist puzzle of Eastern enlargement; Part II. Expanding the Western Community of Liberal Values and Norms: Eastern Enlargement in a Sociological Perspective: 4. Sociological institutionalism and the enlargement of regional organizations; 5. Eastern enlargement and the Western international community; 6. The event history of enlargement; Conclusion: the sociological solution to the enlargement puzzle; Part III. Association Instead of Membership: Preferences and Bargaining Power in Eastern Enlargement: 7. Process hypotheses; 8. State preferences and the initial enlargement process; Conclusion: the double puzzle of Eastern enlargement; Part IV. From Association to Membership: Rhetorical Action in Eastern Enlargement: 9. Rhetorical action; 10. The decision to enlarge NATO; 11. The decision to enlarge the EU; Conclusion: solving the double puzzle of Eastern enlargement; Strategic action in international community: concluding remarks; Appendix (interviews); List of references; Index.