Thesis advisor: Raquel Muniz Castro / Researchers and educators recognize the benefits of developing students’ social and emotional competencies, but there is little research about the impact of leadership practices on the social and emotional competencies of adults in schools. The purpose of this qualitative case study was to investigate the relationship between leadership practices (i.e., what leaders think and do) that promote SEL opportunities, and how they shape the work of mental health staff (MHS) — defined in this study as, school counselors, and nurses. Findings indicated that school-based leaders promoted SEL opportunities for MHS when they (1) provided time to meet, (2) provided resources for professional development, (3) provided feedback through dialogue, (4) accessed MHS’ expertise through dialogue, and (5) provided coaching. These leadership practices shaped the work of MHS proactively. These findings suggest that principals should use social awareness to diagnose issues within the school, engage in responsible decision-making to set direction, and promote relationship-building to convince MHS to implement a plan. / Thesis (EdD) — Boston College, 2020. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Leadership and Higher Education.