This paper addresses the design problem of providing IT support to organizational knowledge creation within a geographical cluster. This study is based on a design science approach that serves to successfully introduce and implement a new IT artefact as a tool for interorganizational knowledge management. We draw on a case study of developing a portal for mapping competencies in an IT cluster in France. Abstracting from the experience of building this system, we developed an IS design theory for collaborative interorganizational knowledge management systems.