A discussion on the pitfalls of studying adolescent psychiatric breakdown emphasises two difficulties, firstly that of delineating the age of adolescence, and secondly the difficulty in applying adult diagnostic criteria. A study of 52 adolescents has been made to establish an initial, and a two year follow-up diagnostic formulation, and to attempt through a detailed survey of the adolescent's early history to identify prognostic indices. The difficulty of formal diagnoses is shown, but prognostic factors of relevance can be identified in the group which have helpful predictive value. Outcome in a group of 50 treated adolescents showed a satisfactory conclusion at two year follow-up, in 70% of cases.