Positive behavioral supports (PBS) have been receiving increased visibility and use in schools nationally. In the state of Washington, schoolwide and individualized positive behavioral supports were recommended as a model for schools by the state agencies of education and human service in 1999. Since then, four demonstration schools have been implementing schoolwide PBS strategies and supports targeted to reach the needs of all students in the school. In this article, we report school-level changes as assessed by leadership teams in the school, along with student-level changes in social skills and problem behaviors. Results are reported on a sample of 68 typically developing students and 56 students who were considered at risk of developing emotional or behavioral problems. Results suggest that the schools made consistent progress from 1999-2002 in implementing the schoolwide PBS model and that students' social skills improved while their problem behaviors decreased. In addition, social skills and behavior problems were found to be related to the number of office referrals students received. Finally, student referrals to prereferral and multidisciplinary team meetings were at or below expected levels, and less than 25% of at-risk students were identified for special education services. (Contains 5 tables and 3 figures.)