Introduction: Diversity and Disciplinarity in International Relations Theory. 1. International Relations and Social Science -- 2. Normative International Relations Theory -- 3. Classical Realism -- 4. Structural Realism -- 5. Liberalism -- 6. Neoliberalism -- 7. The English School -- 8. Marxism -- 9. Critical Theory -- 10. Constructivism -- 11. Feminism -- 12. Poststructuralism -- 13. Postcolonialism -- 14. Green Theory -- 15. International Relations Theory and Globalization -- 16. Still a Discipline After All These Debates?