A comparison of two groups of psychiatric patients is presented. About 600 psychiatric patients treated in general mental hospitals served as a reference group for the cohort of the Follow-up Project Psychotherapeutic Communities. Some methodological aspects of the use of reference groups are discussed. The procedures which were used in matching both groups are described. The results show that the former clients of psychotherapeutic communities (neurotic as well as psychotic) are less frequently readmitted during a follow-up period of five years, as compared with the reference group.