The Canadian Occupational Performance Measure (COPM) is a measure of a client's self-perception of occupational performance in the areas of self-care, productivity and leisure. The COPM is administered using a semi-structured interview in which the client identifies significant issues in daily activities which are causing difficulty. Extensive pilot testing of the COPM has been completed with 268 clients in communities across Canada and in New Zealand, Greece and Britain. Results indicate the COPM has a median administration time of 30 minutes, is able to identify a wide range of occupational performance issues and appears to be responsive to changes in perception of occupational performance over time. A number of clinical and measurement issues centering around the interview, test construction, scoring, timing of the assessment, respondents, and the assessment process are discussed.