Policy overlap between the EU and the OSCE first and foremost exists in the realm of promoting democracy, rule of law, human rights, or conflict resolution and post-conflict rehabilitation and peacebuilding. This study is aiming at identifying co-operation problems originating from the EU’s and the OSCE’s strategic cultures in the realm of conflict prevention and conflict resolution. Concerning method, this paper relies on (soft) text analysis. However, additionally operational policies are taken into account in order to see whether actors’ words are matched by deeds. Evidence for material factors will be balanced against ideational factors’ impact on the inter-institutional co-operation in order to generate plausible evidence for the relative importance of strategic culture. What are the major policy conflicts on the level of inter-institutional cooperation in general and on the operational level in particular concerning the realm of conflict prevention and conflict resolution?