The purpose of this study was to investigate a test procedure to determine auto mechanic know-how. Participants were allowed to look at, feel, and smell a number of defective vehicle parts in order to identify the part, indicate its condition, decide why it failed, and decide on whether to reuse it or not. The test was divided into 10 categories which are recognized in the trade as specialties. The four groups sampled included: (1) automotive service technicians working full-time in the trade, (2) automotive technician teachers, (3) automotive technician trainees, and (4) automotive parts men. As a result of this study, the hypothesis that diagnostic and prescriptive ability of an individual in examining parts or specimens carries with it the implication of his ability to perform the manipulative tasks associated with those parts in the vehicle was accepted. It was also concluded that the instrument that was developed can discriminate between groups or individuals with various levels of automotive trade competence. (Author/GEB)