European integration follows a puzzling stop-and-go pattern that traditional international reations theories cannot fully explain. The predominating paradigms only account for either the achievements or the setbacks of the integration process. An information based explanation makes it possible to move beyond structural accounts provided by realist and functionalist scholarship. Such an approach yields solid micro-level foundations of international bargaining and focuses on leaders' use of threats in negotiations about regional cooperation. Situations involving governments agreeing on the necessity of further integration, but disagreeing about its level, create room for strategic manipulation of information asymmetries. This type of uncertainty stems from the manipulator's information and control advantages concerning domestic costs. The analysis of different summit meetings demonstrates the empirical relevance of such maneuvers for the dynamics of European integration.