Traditional organizational structures evolve towards online business using modern IT – such as cloud computing, semantic standards, and process- and service-oriented architectures. On the technology level, Web services are dominantly used for modeling the interaction points of complex Web applications. So far, development of Web services has matured on the technical perspective considering for example the development of standards for message exchanges and service coordination. However, business concepts, such as economic assets exchanged in transactions between cooperating actors, cannot be easily traced in final Web service specifications. As a consequence, business and IT models become difficult to keep aligned. To address this issue, the authors propose an MDD approach to elicit business services and further software services using REA business model as the starting point. The proposal focuses on a value-explorative elicitation of business services at the top level and model transformations using UML 2 to the system level by utilizing well-defined mappings.