Professional school counselors play an integral role in the academic, personal/social and career development of children. Each day, they are charged with addressing student mental health needs (Burnett-Zeigler & Lyons, 2012; Green et al., 2014), expected to attend to academic issues such as assisting with the college matriculation (Bryan, Moore-Thomas, Day-Vines & Holcomb-McCoy, 2011), all while managing non-counseling related duties (Perera-Diltz & Mason, 2008). Unlike individuals in other counseling fields, professional school counselors serve their students without the benefit of clinical supervision (Uellendahl & Tenenbaum, 2015). For most school counselors, the only clinical supervision they receive occurs during the internship component of their graduate program. Therefore, the on-site supervision received during the internship was the focus of this research study. The purpose of this study was to examine the relationship between the supervisory working alliance, level of disclosure and satisfaction with supervision and school counseling self-efficacy. A total of 179 participants completed a web-based survey consisting of a demographic questionnaire and four standardized instruments: The School Counselor Self-Efficacy Scale, the Supervisory Working Alliance Inventory – Trainee Version, and the Quality of Supervision semantic differential. A standard multiple regression of the data indicated that level of disclosure contributed significantly to self-efficacy, accounting for 12% of the variance. These results can be used to inform the field of counselor education as well as professional school counseling. Future research is encouraged to identify which factors, if not the supervisory working alliance and satisfaction with supervision, make a significant impact on school counseling self-efficacy.