Graduation date: 2008School counseling site supervisors provide a critical contribution to the professional development of master's program school counseling interns; however, their training needs remain unidentified in the literature. To that end, the purpose of this quantitative study was to explore the training needs of site supervisors of master's program school counseling interns in the Pacific Northwest via the construct of self-efficacy. To initiate this exploration, the Site Supervisor Self-Efficacy Survey (S4) was developed. This 28 item web-based survey investigated respondents' (N = 147) perceived self-efficacy in relation to supervision as well as hours of supervision training received. Results (82% return rate) indicate that many site supervisors have little or no supervision training, and that supervisor self-efficacy appears relatively strong--consistently so for those with over 40 hours of training. A partial correlation indicates a slightly positive relationship (r = .202, p < .009, one-tailed) between the hours of supervision training received and perceived self-efficacy regarding supervision. Implications regarding site supervisor training and suggestions for future research are offered.