1. This paper is part of a larger research project guided by the following questions: What is the nature of psychiatric symptoms in adolescent patients? How do the symptoms in this group compare with those of a non-patient group? What happens to the symptoms of both groups as they pass through a substantial part of their adolescence?2. The method consists of a 5-year study of 101 adolescent outpatients and a matched control group of 101 non-patients.3. This paper presents the results of the initial evaluation of the patient group as follows:i) Five syndromes have been defined that represent 84 of the 101 patients as follows: thinking disorder—16, psychoneurosis—38, acting-out—17, depression—7, and hysterical personality disorder—6.ii) The clinical and dynamic relationships of the 5 syndromes are presented. For example, acting-out showed more prevalence in boys, 15 or under, had an early age of onset, a long duration, and an impaired relationship with mother.iii) For several syndromes this information suggests hypotheses as to both the origin and the clinical nature of the disorder.Abstract Teaser