Coopetition has been defined as an approach to managing that combines competition and cooperation. It transcends the traditional paradigms of competition and cooperation in an effort to achieve the advantages of both. As an inter-organizational relationship that is of a higher complexity than either simple competition or cooperation, coopetition presents both conceptual and practical challenges for business managers and researchers in the strategy field. In this paper we present a systemic approach to modeling coopetition between firms that provides a methodology for analyzing the strategic incentives for enterprises to engage in coopetition relationships and the organization design required to address the complexities inherent in such multi-faceted relationships. Our approach comprises a modeling technique called Systemic Enterprise Architecture Method (SEAM) that incorporates important conceptualizations adapted from competence based management (CBM) theory. We illustrate our approach by applying it to the case coopetition between IBM and Apple in the development of PowerPC CPU.