The rehabilitation model of corrections began in the 1930s and reached its high point in the 1950s. Qualified staff members were expected to diagnose the cause of an offender's criminal behavior, prescribe a treatment to change the individual, and determine when that individual had become rehabilitated. Group therapy, counseling, and behavior modification were all part of the approach. These techniques did not work with all inmates, especially with those convicted of violent crimes; most states did not budget enough money for their correctional institutions to achieve these goals; and there were too many prisoners for the prison staff to treat effectively.