A group of 14 institutionalized delinquent girls received individual psychotherapy from one therapist who interviewed the girls, usually for 50 minutes twice a week for an average of 23 interviews. Fourteen control subjects received only the institutional training. Psychological and behavioral changes were compared using a behavior rating scale, six psychological tests, and a parole adjustment rating schedule. The therapy group showed improvement in behavior ratings by teachers and counselors and showed significant improvement on the following scales: psychopathic deviate; perception of socially desirable traits; schizophrenic trends; manifest anxiety; the anxiety factor; delinquency; tenseness; excitability; repression; emotional stability; alertness; friendliness; problem solving; hostility; assault; irritability; suspicion; verbal hostility; adequate perception; and distorted perception. The control group did not (p=.05). The control group showed larger improvement on scales of suspiciousness and ego strength of the Minnesota Multiphasic Personality Inventory and deterioration on problem solving, realistic and inappropriate perception, guilt feelings and latent hostility. A followup study 2 years later showed trends toward better parole adjustment by the therapy group. Case summaries are presented for the subjects. (LE)