A wide variety of approaches can be applied under the heading of case study research; this paper explicitly discusses the range of the alternatives. Many papers discussing case study research emphasize one particular variation of case study research only. The current paperprovides an overview of the various uses of case study research in the information systems field by describing the different ways in which case study research can be used, using examples from published IS literature for illustration, and providing references to other method papers for more detailed discussion of each alternative. Researchers are reminded that case study research can be used in the positivist and interpretivist traditions, for testing or building theory, with a single or multiple case study design, using quafitative or mixed methods. The range of case study research alternatives makes it a highly versatile research strategy for IS.