With the growing density and the plethora of security organisations on the regional and international level, the research programme on interorganisational relations has received increasing scholarly attention. The complexity of European security – in light of the Ukraine conflict since 2014, Russia’s more assertive foreign policy behaviour, and on-going crisis management operations in the Africa, the Mediterranean Sea and Middle East – has revived EU-NATO cooperation. The analysis from the perspective of member states and how they can be positioned in the EU-NATO interorganisational relations, however, has received little exploration. This article, therefore, addresses the roles and positions of member states within the relations between the EU and NATO as Europe’s prime security organisations. Member states have numerous political strategies at their disposal to trigger, strengthen or obstruct interorganisational relations, ranging from forum-shopping to hostage-taking and brokering. Drawing on insights from regime theory, network analysis, organisation theory and interorganisationalism, this article proposes a typology of member states in EU-NATO cooperation. Against the backdrop of this special relationship, the typology is developed which aims to detect and illustrate member states’ positions and strategies.