This study explored the supervision training needs of site supervisors of master's program school counseling interns via the construct of self-efficacy. Using the Site Supervisor Self-Efficacy Survey developed for this study, the authors surveyed school counseling site supervisors in the states of Oregon and Washington (N = 147) regarding their hours of supervision training and their supervisor self-efficacy. Results indicated that 54% of school counseling site supervisors had little or no counseling supervision training. Supervisor self-efficacy appeared to be relatively strong, consistently so for school counseling site supervisors with over 40 hours of supervision training. A partial correlation indicated a slightly positive relationship between the hours of supervision training received and perceived self-efficacy regarding supervision. Implications regarding school counseling site supervisor training and future research are offered.