There are many questions about the role of sociotherapists in institutions for the mentally ill and consequently also about the required content of their training program. The sociotherapist is part of a team of other therapists; he must systematically and purposefully support the patient's behavior in intramural and extramural situations. The therapeutic value of sociotherapy depends greatly on the theoretical model of treatment in a particular institution. The social learning treatment model integrates investigation and treatment. The client's problematic behavior is considered in the context of the present situation as well as in the context of the patient's development in earlier learning situations. His present behavior must be placed between its causes and its results. Both factors show links with earlier social learning situations and may lead to identification of the essential problem. This problem identification, however, does not automatically result in different behavior. New behavior must be learned in practical social situations. Sociotherapists, sport-therapists, occupational therapists, other therapists, and even other patients in the institution may well contribute to the process of learning new social behavior, be it through a systematic treatment or informally through the environment of a 'therapeutic society.' The sociotherapist's training should cover observation, reporting, and discussion techniques as well as the methods of the social learning approach. This treatment model is less successful when it is compulsory, as with delinquents, but there are indications that the learning of new behavior may change patients' negative attitudes toward treatment. If therapists can reduce patients' distrust through dialogue, patients may build new relationships with their surroundings. Special activities such as family contacts, discussion groups, and sports events in regional leagues permit patients to be involved in extramural situations without risks to society. Eleven references are provided.