In comparison with traditional experimental design, which is concerned with what happened, a case study approach is more appropriate for answering the question of why or how something happened. As an alternative complementary-vocational-education-evaluation approach, the case study attempts to describe and analyze some program in comprehensive terms with its idiosyncracies and complexities, frequently as it unfolds over time. Case studies have advantages--opportunities to formulate problems as the evaluation progresses, modify data categories constantly, and reduce distortion of variables--and limitations--need for special training in conducting them and careful definition of case, their length, and their generalizability. Twelve steps comprise the three stages in the case study process: pre-fieldwork; fieldwork; and analysis, verfication, and synthesis. The preliminary steps involved in case study design are setting boundaries, defining the unit of analysis, selecting a site, establishing initial contacts, developing data collection systems, and defining fieldwork procedures. The field work stage involves staff training, logistics of field operations, and data collection using qualitative methods (interviewing, observing, and gathering data unobstrusively). Steps in the final stage--analysis, verification, and synthesis--include analyzing data, reporting the findings, and utilizing the findings. (A case study puzzle and annotated bibliography are appended.) (YLB)