The concept of sustainable development is more a multi-dimensional theory then a simple decision-making tool. Therefore it is not easy to integrate the concept of sustainable development into the process of strategy development. But top-management needs a manageable tool to integrate the concept of sustainable development into the process of strategy development. The purpose of this work is to examine the strategic implications for energy utilities in the deregeulated electricity and gas market with regard to the concept of sustainable development. The result of this research is the development of a concept for strategy development for energy utilities which integrates all dimensions of sustainable development. The research focuses on the process of strategy development and not on the financial impact of different strategies. Thus this research work can be assigned to the research field of strategic processes. The aim of the esearch is to asnwer the following question: Which strategic instrument allows energy utilities to integrate the concept of sustainable development into the process of strategy development?