This dissertation studies nuclear crisis behavior. Specifically, it theorizes behavior between middle powers with nuclear weapons that are nested within a world with larger hegemonic states. The situation represents a paradigm shift from the bipolar context of the Cold War where all nuclear crises involved one or both superpowers, thereby implying an absence of stronger third parties that could fundamentally alter their crisis behavior. We have focused on the India-Pakistan rivalry, and specifically on their three nuclear crises since South Asia's overt nuclearization: the 1999 Kargil crisis; the 2001-02 standoff; and the 2008 Mumbai crisis. These three case studies form the universe of crises between two middle power nuclear states with stronger third parties present to influence their behavior. Using the structured focused comparison method and relying on existing empirical analyses of these crises, interviews with relevant officials and experts, and newspaper archival research, we have process-traced the key developments in each crisis to identify the processes and mechanisms underpinning behavior. The dissertation argues that middle power nuclear crises ought to be seen as trilateral engagements that accord a key crisis management role to stronger third parties. Crisis behavior can be best understood through "brokered bargaining" - defined as a three-cornered bargaining exercise between the two principal antagonists and a third party which is primarily seeking crisis de-escalation. Brokered bargaining theory predicts that this three-cornered engagement will play out in the expected manner each time a middle power nuclear crisis occurs as long as the outside actors do not intervene as competitor third parties. We reject theories that posit the dynamics of bilateral nuclear deterrence as the principal drivers of de-escalation, and equally, analyses that see third parties as standalone explanations for peaceful outcomes. We contend that it is the process of trilateral interaction encompassed by the brokered bargaining model and marked by a recursive interplay of perceptions, expectations, incentives, and strategies of the three actors that shapes crisis behavior, and in turn, trajectories and outcomes. The research is generalizable to potential nuclear rivalries in the Middle East and remains relevant to the Sino-Indian dyad and rivalries on the Korean peninsula. / 2019-05-31