The effectiveness of the course was measured by contrasting the performance of officers undergoing the training with that of a control group before the course, immediately afterwards, and six months later. During the assessment, performance indicators were applied to simulated interviews which were recorded on video, and to operational audiotaped interviews conducted in the officers' forces. Students and controls were also tested on their knowledge of interviewing techniques. The results showed that on a written examination, students performed better than controls. In the simulated interviews with witnesses and suspects, the course participants improved from their pre-course scores and this improvement was maintained at the 6-month follow-up. The assessment also demonstrated that students performed better in operational interviews with suspects. 6 figures, 1 table, 6 references, and 2 appendixes