The decision of the Cameron government to renegotiate the terms of UK membership and to hold an in-out referendum has triggered a novel process in European integration: differentiated disintegration, the selective reduction of a member state’s level and scope of integration. The article starts from an established post-functionalist explanation of differentiated integration and claims that it also explains demand for disintegration. By contrast, the institutional and material bargaining power of states demanding disintegration is considerably lower than that of states demanding opt-outs in the context of integration negotiations. Consequently, demanders of disintegration moderate their demands and make concessions to the EU in the course of negotiations. The ongoing UK-EU disintegration negotiations confirm this expectation.