The paper has two main aims. First it seeks to explore whether security cooperation between the EU and China is taking place, and if so, whether it is evenly spread across a number of security dimensions. Second it intends to investigate the underlying motives or drivers that either facilitate or inhibit EU-China security cooperation. Further, it will explain why the EU rather than EU member states is chosen as the unit of analysis, explore the development of EU-China security relations, and illustrate how historical legacies, identity aspects and differences over key issues, such as sovereignty and territorial integrity, affect EU-China security relations. In addition, it will deal with the theoretical and conceptual underpinnings of the study on EU-China security relations, paying particular emphasis to the concepts of diffusion and convergence. Whether or not EU-China security cooperation converges in one of the ten chosen security dimensions will be assessed by the degree of policy conformity the EU and China are able (or unable) to obtain with regard to threat perceptions and policy response thereto. Attention will be devoted to diffusion factors which can affect changes in the perception of threats and response thereof. Among these factors are changes in (geo-political) structure, interests and norms. A further objective of the paper will be to explore whether policy convergence on threat perceptions and response thereto might be a precondition for joint action, or whether practical cooperation can take place without prior policy convergence between the EU and China. The paper will round off with a short section introducing the security dimensions that are being examined in the more detailed study on which this paper is based.