Services can be characterized as activities in which providers and customers co-create value. The need for a tight collaboration between providers and customers is thus an important distinguishing aspect of services compared to products. Traditional software engineering methodologies provide limited support for collaborative processes at runtime and are therefore not directly applicable to service engineering. In particular, the design of coordination mechanisms between service provider and customers as well as the design of a common vocabulary in an interorganizational setting is not adequately addressed. To face these shortcomings, we present an interdisciplinary approach integrating just recently proposed Web service engineering methodologies with market and ontology engineering to one coherent service engineering methodology.