ABSTRACT Liberal intergovernmentalism (LI) posits that member states’ preferences are domestically shaped and align with the positions of the largest states. However, during EEAS negotiations, major states had divergent views on Common Foreign and Security Policy (CFSP) integration, risking nonagreement. Despite the inability to counter external threats effectively, states prioritised sovereignty and national interests. This paper, based on interviews with member states and EU institution representatives involved in the bargaining process, evaluates LI’s applicability to CFSP integration. It examines the preference formation of France, Germany, and Spain during the creation (2002–2003) and design (2010) of the EEAS, the last revolution in the institutional framework of the CFSP and the most innovative body established by the Treaty of Lisbon (2009). The study contributes theoretically and empirically to understanding LI. Since member states follow an exogenous but not liberal preference formation process, it concludes that LI should be revised.