New developments in the Common Security and Defence Policy (CSDP), such as PESCO or the European Defence Fund (EDF), challenge the differentiated integration framework put forward by Frank Schimmelfennig, Dirk Leuffen and Berthold Rittberger: this policy is not and may have never been a case of low vertical integration and uniform horizontal integration. This paper presents an amended version of their framework based on constructivist institutionalist accounts of European integration. First, it discusses their explanatory variable. Rather than interdependence per se, this paper argues that it is the construction of interdependence that matters in order to understand integration. Second, rather than focusing on primary EU law, which often obscures many policy dynamics, this paper builds on legal, institutional and practice-level elements of CSDP. Based on these changes, this paper argues that national and European actors have constructed interdependence in this policy domain, by tying together armament-related issues with single market regulation and by linking armament-related issues with CSDP’s operational-military requirements around the issue of capabilities. These processes explain CSDP’s policy-making hybridity, i.e. the combination within CSDP of a more intergovernmental policy-making mode (especially but not restricted to operational-military elements) with more supranational elements (especially but not restricted to industrial armament-related elements), as well as its horizontal differentiation. The conclusion discusses the theoretical implications of policy-making hybridity.< Réduire