This study aims to understand the causes of cooperation during transition processes in the Middle East and North Africa (MENA) and their impact on transition outcomes. Even though the literature suggests that different patterns of cooperation among actors led to diverging transition outcomes in the MENA, we still do not know the causes behind these different patterns. This study moves away from cooperation during transitions and examines the underlying causes of these different patterns in order to explain the diverging transition outcomes. I argue that origins of a strategic cooperation during a transition, and a successful transition outcome in return, can be found in the period before the transition attempt. Cooperation during a transition requires the resolution of commitment problems among actors. If the main opposition actors build a successful coalition bloc and work against the regime together under authoritarianism, they develop common grounds, organizational and social capital, trust and a shared vision towards democracy building. Once a democratic transition process starts, these mechanisms provide a solution for commitment problems and facilitate cooperation as a transition strategy among these actors. Without these mechanisms, new rules and challenges of the transition process hinders such cooperation and a successful transition. The analysis of two failed (Algeria in the early 1990s and Egypt during the Uprisings) and one successful (Tunisia) transition attempts indicates that this pattern goes beyond the Arab Uprisings. In both Algeria and Egypt, the main opposition actors did not have a history of successful coalition building under authoritarianism. When the transition process started, groups could not overcome commitment problems and meet in a common goal. In Tunisia, on the other hand, the opposition actors from different ideological camps had a history of cooperation under Ben Ali regime and founded a strong inter-ideological coalition bloc named October 18 Collective. These experiences provided mechanisms to overcome the commitment problems and helped the parties to pursue cooperation as a strategy for transition. When transition process was in jeopardy, the past experience of coalition building and dialogue proved to be helpful to overcome challenges. This study is based on a 12-month fieldwork in Algiers, Tunis and Istanbul which includes over 100 interviews with primary and secondary actors and archival research as well as an original elite survey with experiments in Tunisia. The study combines experimental and qualitative evidence and meticulously links the experiences under authoritarianism to cooperation during transition using process tracing.