International relations emerged as a distinct academic discipline in the early twentieth century, but its philosophic foundations draw on centuries of thinking about human nature, power and authority, justice and injustice, the idea of sovereignty and the implications for relations within and between political communities. The historic sources of these ideas appear to draw largely on European or Western experiences but, as this book shows, influences have emanated from much further afield, while contemporary thought is becoming more open to insights from non-Western sources. In this fully updated and expanded fourth edition of her popular text, Stephanie Lawson retains a broad world historical and contextual approach to the central themes and theoretical perspectives in IR, while also addressing the most pressing issues facing the world today. Topics covered include the emergence of states and empires, theories ranging from classical realism and liberalism to postcolonial and green theory, twentieth-century international history, security and insecurity, global governance and world order, international political economy and the prospects for a 'post-international' world in an era that has seen both deepening globalization and accompanying challenges to the sovereign state, as well as the reassertion of nationalist ideas around the world. With a range of additional pedagogical features to assist learning and class discussion, this lively and accessible text is an ideal primer for beginner and intermediate students alike.