This chapter offers an analysis of the political and security dynamics in Southeast Asia, contextualized through the application of diverse theoretical frameworks within the field of international relations. It examines how the colonial legacy, the influences of the Cold War, and the rise of globalisation and regionalism have combined to shape the contemporary political structures of Southeast Asia. The chapter analyses the interplay of realism, liberalism and constructivism and shows how realist power struggles, liberal institutional cooperation and constructivist norms of identity and regionalism influence security policy in the region. Particular attention is paid to the role of ASEAN as a stabilising force. It shows how regional cooperation helps to manage disputes and promote dialogue despite complex inter-state relations. The chapter also explores critical theories and the human security paradigm and examines how economic dependency, authoritarianism and internal conflict affect Southeast Asia’s stability. By integrating these frameworks, this chapter contributes to a nuanced understanding of Southeast Asia’s unique political landscape and security challenges in a rapidly evolving global order.