This module surveys the main explanatory theories in the academic discipline of International Relations (IR) as they relate to peace, conflict and security. It introduces the most influential frameworks for explaining different types of conflict and insecurity in international relations, with a focus on inter-state war but inclusive of other contemporary security issues. Attention is paid to the differing assumptions and arguments advanced by different social scientific perspectives on international politics. Attention will be paid throughout to both quantitative and qualitative evidence relevant for evaluating the central hypotheses of the main theoretical perspectives, and the guidance from the philosophy of science about the assessment of theories. The aim is to equip students with the necessary conceptual and analytical tools that can then be applied to their own specific areas of interest or field of research. By the end of the module students should be able to understand the key theoretical debates in the subject of IR, especially as they relate to peace, conflict and security.