Designing software platforms to support the activities of partially virtual communities (PVC) is a challenging task since the supporting services must evolve continually according to the community evolution. Moreover, unsuitable supporting services usually lead the community to its demise. Therefore, these platforms must count on a flexible architecture that provides suitable services as a way to support interactions among community members, and thus contributing to keep the community sustainability. This article proposes a software architecture that helps software designers to address this challenge. Such a model can be used not only to ease the architectural design process, but also to evaluate already implemented PVC supporting systems. The article also shows a preliminary evaluation of both roles of the proposed model and discusses the obtained results. © 2012 Springer-Verlag.