Supervision is a critical element in the professional identity development of school counselors; however, available school counseling-specific supervision training is lacking. The authors describe a 4-hour supervision workshop based on the School Counselor Supervision Model (SCSM; Luke & Bernard, 2006) attended by 31 school counselors from three southern U.S. school districts. Employing a pre-experimental pretest-posttest research design using the Site Supervisor Self-Efficacy Survey-revised (DeKruyf, 2011), the authors found a significant positive relationship (t (30) = 9.31, p < 0.001; Cohen's d = 1.67) between supervision training and supervisor self-efficacy. These findings bolstered the efficacy of the SCSM. The authors discuss research and practical implications of this study.