This article offers an overview of the follow-up project Psychotherapeutic Communities on which from 1984 until 1987 nine articles were published in this journal. We comment upon the question to what degree this long term project has contributed to our knowledge of the condition of patients after discharge. Moreover attention is paid to the controversial problem of selecting adequate criteria that can give a plausible answer to this question. In this project (long term) well-being, readmission and detachment from professional care were the major criteria. As far as outcome of PTC-treatment is concerned, enough positive indications were found to justify the existence of the forms of clinical treatment. Nevertheless many more (partly new) questions appeared to be left unanswered. Because of the duration of this type of research we investigated the updatedness of our findings and assessed that there is no reason no consider them obsolete. An evaluation of the many methodological and practical obstacles that were encountered, leads to the conclusion that the utility of the project is satisfactorily. We plea for continuation of this type of research, albeit in an adaptated form.