This book constructs a new scientific explanation of the decision making process underlying conflict escalation. It draws on the literature in political science and psychology. First, the structural variables embedding the decision making process in a conflict are extracted from empirical macro-level studies on peace and war. Then, the psychological triggers of escalation underlying the decision making process in a conflict are examined. Four triggers are identified - frustration, threats, norm violations and sunk costs. For each of these triggers, the theoretical background, the empirical findings and their implications on conflict escalation are examined. Finally, the psychological triggers of conflict escalation and the structural variables of conflict escalation are discussed in relation to the inherent dynamics of escalation processes.