Advances in applied sport psychology will require the application of experimental, quasi-experimental, and nonexperimental research methodologies. The case study has stimulated important discoveries in many areas of psychology, although its limitations for drawing causal inferences are widely acknowledged. Case studies vary markedly in their design and methodology, however, and these differences dictate the extent to which alternative explanations can be ruled out on procedural or empirical grounds. The present article discusses design considerations that influence the construct validity, internal and external validity, and reliability of case reports. The application of techniques such as pattern matching, time-series analysis, and goal-attainment scaling to case study methodology is also described. Finally, guidelines for planning and reporting case studies in a manner that enhances their scientific and practical contributions are discussed.