The 1990 reauthorization of PL 94-142, the Individuals with Disabilities Act (IDEA), emphasized the need for applied research in schools to prevent the development of emotional disturbance. Prevention research then led to mandates in IDEA 1997 that schools must develop positive behavior interventions and supports (PBIS) for children and youth whose behavior impeded their educational performance. This chapter describes how the ensuing research and implementation regarding each of the three-tiers of PBIS have influenced the educational outcomes of students with EBD. Recommendations for school staff using the three-tiered PBUS model are provided so that students with EBD can benefit from implementation of PBIS structures and supports. (Contains 1 figure and 3 tables.) [For complete volume, see ED539318.]