Level systems provide systematic support for teachers and students who need additional behavior support. The purpose of this study was to evaluate the perspectives of faculty members from a self-contained school, for special education students with severe behavior needs, which has sustained the use of a school-wide, behavior management level system for nearly 30 years. A total of 11 faculty members were interviewed using the critical incident technique, a qualitative methodology used as an exploratory tool in early stages of research. Interviews detailed the observable behaviors and specific events, critical incidents, that helped or hindered the sustainability of their school's level system. Faculty identified eight helping categories, six hindering categories, and six "wish list" categories, items participants wished had happened or could happen in the future. Helping categories included building rapport and teaming; collecting, recording and using data; communicating and collaborating; schoolwide consistency; relationships and student feedback; student engagement and buy-in; faculty buy-in and adaptability. Hindering categories included scoring and accountability inconsistencies; philosophical differences; insufficient staff training and experience; multifaceted system requiring nuanced decision making; staff mental health concerns; and community factors and external pressures. The findings of this study illustrate the importance of varied communication portals to support sustainability.