Critical realism has been proposed as an alternative philosophical paradigm to positivism and interpretivism, but few papers have offered guidelines or suggestions for applying this philosophy to actual research methodologies. This article proposes a set of methodological principles for conducting and evaluating critical realism-based explanatory case study research within the information systems (IS) field. The principles are consistent with the ontological and epistemological assumptions of critical realism, which are discussed along with a brief comparison to the contrasting assumptions from positivism and interpretivism. Examples from published case study articles in the IS research literature are discussed in order to demonstrate each principle in more detail.