Preface; 1. Introduction Katharina Holzinger, Christoph Knill and Bas Arts; 2. State of the art - conceptualising environmental policy convergence Katharina Holzinger, Helge Jörgens and Christoph Knill; 3. Theoretical framework: causal factors and convergence expectations Katharina Holzinger and Christoph Knill; 4. Research design, variables and data Stephan Heichel, Katharina Holzinger, Thomas Sommerer, Duncan Liefferink, Jessica Pape and Sietske Veenman; 5. Degree and direction of environmental policy convergence: analysis of aggregate data Thomas Sommerer, Christoph Knill and Katharina Holzinger; 6. The pair approach: what causes convergence of environmental policies? Thomas Sommerer, Katharina Holzinger and Christoph Knill; 7. The gap approach: what affects the direction of environmental policy convergence? Bas Arts, Duncan Liefferink, Jelmer Kamstra and Jeroen Ooijevaar; 8. Conclusion Christoph Knill, Katharina Holzinger and Bas Arts.