This chapter explores the intertwined phenomena of aggression, conflict, dispute, violence, and war, situating them within a multidisciplinary framework that spans ethology, sociology, psychology, anthropology, and law. It begins with aggression, a universal trait across species, debated as either innate instinct or learned behavior. From Hobbes and Rousseau to Lorenz and de Waal, aggression is examined both as a destructive force and as a relational mechanism that regulates competition, social change, and cooperation. Conflict is then analyzed as the bridge between individual behavior and social structures. Drawing on classical and contemporary theories—from Simmel, Coser, and Dahrendorf to game theory and Rapoport’s tit-for-tat strategy—the chapter highlights conflict’s dual nature as both disruptive and integrative. Escalation dynamics, polarization, and cultural differences in conflict management are explored alongside the adaptive and creative potential of integrative solutions. The section on disputes frames them as institutionalized expressions of conflict, emerging through processes of naming, blaming, and claiming. Empirical debates on the so-called “litigation explosion,” cultural and institutional determinants of litigiousness, and the rise of hybrid mechanisms like “litigotiation” illustrate how legal systems shape, and are shaped by, disputing behavior. Critiques of dispute resolution theories are addressed, especially concerns over psychological reductionism, functionalist biases, and neglect of power asymmetries. Violence and war are treated as extreme but socially embedded manifestations of conflict. Collins’ micro-sociological theory of situational violence and Pinker’s evolutionary taxonomy are juxtaposed with perspectives on structural and ideological violence, as well as historical shifts in organized warfare. The chapter also engages with evolutionary hypotheses of human self-domestication and the “goodness paradox.” Finally, conciliation and peacemaking practices are examined, from primate reconciliation rituals to human negotiation, mediation, and reconciliation rites. The chapter argues that while aggression and conflict are inevitable dimensions of social life, their transformation through legal, cultural, and moral frameworks remains essential to reducing violence and sustaining cooperative societies.