The International Atomic Energy Agency (IAEA) bases its technical and scientific programme on voluntary contributions from Member States, constituting the Member States Support Programme (MSSP). The European Commission Cooperative Support Programme (EC-SP) started in 1981 to support IAEA activities in the field of nuclear safeguards. Since its beginning, the EC-SP has been operated by the European Commission's Joint Research Centre (JRC) in close collaboration and coordination with the European Commission's Directorate General for Energy implementing the EURATOM treaty. EC-SP tasks provide technology and expertise in technical areas related to the effective implementation of safeguards verification measures including the detection of undeclared materials, activities, and facilities. The EC-SP fosters cooperation with Support Programmes from European Union Member States, as well as with non-EU states with which the European Commission has specific research and development agreements. An example is the Agreement between the United States Department of Energy and the EURATOM Community in the field of nuclear material safeguards and security research and development. R&D activities under this framework are coordinated with the IAEA and complement core EC-SP work. The paper describes the EC-SP, its modus operandi, collaborations, and main activities, namely, (a) the specific R&D work as part of tasks with well-defined milestones and deadlines, (b) training activities and (c) the technical consultancy support to IAEA meetings and expert groups.