Assessment of the Canadian Volunteers in Corrections (CaVIC) program centered on the use of authority by correctional officer and on the effectiveness of correctional workers as role models and reinforcers of anticriminal behaviors. Also assessed were the problem-solving assistant to probationers, the use of community resources, and the interpersonal relationships with probationers. Results were compared between 96 probationers assigned to a professional officer pool of 14 and 94 probationers assigned to a citizen volunteer pool of 60. The comparative research findings described the nature and quality of volunteer supervision of probationers, the differential effectiveness of volunteer and professional supervision with different types of clients, the effects of matching officer and client characteristics, the differential effectiveness of different supervisory practices with different types of clients, and the selection of intermediate behavioral targets. Volunteer and professional supervision differed greatly in terms of the frequency, duration and types of contacts with probationers. Volunteers saw clients in person twice as often and encouraged a socioemotional orientation in contrast to the authority and active counseling orientations of professional officers. There were no significant differences between probation success rates of clients under volunteer and professional supervision. Officer efforts on the authority, anticriminal reinforcement, and problem-solving dimensions were associated with reduced levels of recidivism and were among the most basic elements of effective supervision. A figure, 7 tables, and 11 references are provided.