The expanding popularity of qualitative research, and more particularly case study research, in the field of Information Systems, Organization and Management research, seems to have been accompanied by an increasing divergence in the forms that this research takes, and by recurrent criticisms concerning its rigor. This paper develops a heuristic framework for guiding the design of a rigorous case study depending on the research’s goal and epistemological framework, as well as for guiding its evaluation. It also highlights the fundamental reasons – namely the epistemological ones – for differences in the guidelines offered in the literature for conducting high quality case studies. In agreement with numerous authors, we argue for contingent evaluation criteria. We supplement these authors’ works in two ways: (1) we consider various epistemological frameworks that do not appear in the classifications that they use, especially including critical realism and pragmatic constructivism; (2) we propose a set of contingent criteria to be used as a heuristic device for critically and knowledgeably building rigorous case studies within different epistemological traditions.