The notion of trust or distrust appears in most accounts of cooperation and is, at least implicitly, understood as a primary determining factor for any future collaboration. This is equally true for European integration theory which highlights the importance trust plays in shifting loyalties, reducing transaction costs or forming security communities. Given its importance in influencing cooperative outcomes, it is surprising how little attention trust has received and how seldom the conceptual foundations of trust have been examined. The purpose of this article is to begin to address this shortfall through exploring the concept of trust in European integration theory with a particular focus on the competing and complementing categories of strategic and moralistic trust. This is further complemented by the addition of a case study on EU civil protection as one of the fastest growing areas of European security integration in the European Union.