Abstract: This dissertation is an attempt to seek the causes of peace and war in the process of international crises. It employs strategic bargaining theory to examine how states use both accommodative and coercive means to deal with their conflicting interests during international crises. An international crisis is conceptualized as a process of bargaining between states in the shadow of war, and states' crisis behavior is construed as their bargaining strategies in different situations. In particular, I use the revised Rubinstein bargaining game with war as an outside option to model the process of crisis bargaining. In my study, crisis bargaining is examined in four significant scenarios. The first scenario tackles the ideal situation of complete information, that is, every aspect of crisis bargaining is supposed to be public knowledge. The second scenario considers the factor of risk, that is, war may occur as a consequence of some unexpected accidents even no participant intends to launch it. The third scenario deals with uncertainty, that is, one or more crucial aspect of the crisis bargaining is players' private information that is unknown to the opponent. The last scenario lifts the neorealist assumption of unitary actors of states and assesses the influence of domestic politics on states' crisis behavior. In each scenario, equilibrium analysis generates insights into states' (or leaders') optimal strategies and stable outcomes of international interactions. My dissertation makes four contributions to international studies. First, it addresses the deficiency in traditional rationalist explanations for war and provides both sufficient and necessary conditions for war and peace. Second, it suggests a way to unite causes of peace and causes of war in the process of international crisis. Third, the bargaining approach and equilibrium analysis provide a new perspective to evaluate some conventional views (e.g., the influence of uncertainty). It also casts light on some long-term controversies in international studies (e.g., the debate between the balance-of-power and power-transition theory). Finally, under the help of the Poliheuristic (PH) theory, I propose a solution to test abstract formal models in specific domestic and international contexts.