This grant proposal is a continuation of the program for the systematic study of psychotropic drugs on the Children's Service of Bellevue Psychiatric Hospital, New York. The scope of work has been expanded and specific projects o outlined with an effort for methodological improvement. We wish to concentrate our efforts on autistic schizophrenic and other severely-disturbed hospitalized children. We wish to evaluate the therapeutic effectiveness and safety of new drugs in these children and to coordinate behavioral and biological changes on and off drugs. In addition, we shall evaluate critically the efficacy of behavior therapy with or without drug treatment in young autistic children. Individual patients will be followed longitudinally to evaluate long-term outcome of drug treatment and somatosexual maturation. The studies will be carried out in order to develop a more rational approach in pharmacotherapy for this population, to delineate biologically more meaningful diagnostic categories or subgroups, and to define "drug responders."