The project was implemented in the two comparable institutions of O.H. Close and Karl Holton, both of which were similar in organizational structure, staffing patterns, and physical layout. The respective treatment modality at each institution was characterized by extensive staff involvement in training and program implementation and by exposure of most of the juvenile inmates to intensive treatment. Results showed that both behavior modification and TA treatment modalities produced accelerated achievement test gains, reduced evidence of aggressive behavior, reduced use of lockup, and decreased recidivism. However, the TA program at Close generated more positive youth-staff relations and greater attitudinal gains. In contrast, youths in the behaviorally oriented programs at Holton showed greater positive behavior changes. Parolees from both institutions in the experimental period did better than releasees from earlier periods and releasees from other California youth institutions, with a 10 percent recidivism differential between baseline (1968-69) and experimental periods (1970-71). This difference could not be accounted for by age at release or by any general trend toward lower recidivism. It is concluded that institutionwide high quality treatment programs in California youth correctional facilities can reduce management problems and recidivism rates, although the sustaining of an intensive or innovative program over a long period remains less certain. Two tables and five references are provided.