Environmental policy integration (EPI) is a key defining feature of sustainable development. Despite the fact that EPI has been the subject of much debate both in academic and policy-making circles, conceptual issues relating to EPI have received relatively little treatment. The conceptual work that has been completed on EPI generally fails to place the concept in an appropriate environmental policy context, and this in turn appears to betray the fact that the concept clearly implies a relatively strong revision of the traditional hierarchy of policy objectives. In this article the authors discuss the origins of the concept and provide conceptual clarification regarding its definition and context. Further, the article derives a simple analytical framework consisting of vertical and horizontal dimensions of EPI, which can serve as a useful point of departure for further empirical work on the implementation of EPI.