This article's subject is the cooperation process between organizations that develop and implement innovations in sustainable building. Its main research question is how governmental and commercial organizations organize and structure their joint activities to develop innovations in sustainability. In the search for answers to this question the cooperative activities of innovating organizations are modelled as an interorganizational innovation process. The case study research method is used to investigate the development of interorganizational innovation patterns in sustainability in seven house-building projects in the Dutch residential building sector. The empirical research findings are discussed by means of a comparison with the theoretical framework that includes five complementary stage models of interorganizational innovation processes. The main conclusions of the research are that (1) governmental and commercial organizations that successfully innovate in sustainability go through eight consecutive stages of interorganizational innovation, and (2) perform twenty-two interaction patterns that are part of these stages. © 2007 Elsevier Ltd. All rights reserved.