Case study research is a good fit with many forms of social work practice. Although disparaged as uncontrolled and uninterpretable, the case study has great potential for building social work knowledge for assessment, intervention, and outcome. This article defines case study research, presents guidelines for evaluating case studies, and shows the relevance of case studies to social work research. Guidelines for evaluation also are guidelines for developing and interpreting case studies that will meet the rigorous demands of scientific research and be useful to social work practitioners. © 1994 The National Association of Social Workers, Inc.