Environmental sustainability issues have in recent years received much attention from the side ofenvironmental scientists and economists. There is a broad recognition on the relevance of externaleffects in open and interacting spatial systems. It would be helpful if ecological economic researchwould deploy an integrated analytical framework for investigation the complex nature of suchmulti-disciplinary issues. This paper aims to present a basis for a methodological synthesis foranalysing environmental issues in open economic systems. It seeks to develop an integrativeframework through which a great many ecological-economic studies can be mapped out andrepresented. The focus is the conceptual issues centring around the integration of interactingeconomic and ecological subsystems, inter alia in relation to spatial externalities and ecologicalfootprints. The discussion enables us to build a framework for a systematic categorisation ofvarious types of models for economic-ecological interaction. The paper concludes with somereflections on the way forward.