School-wide positive behavioral interventions and supports (SWPBIS) is a systems-level framework for improving social and academic outcomes for students in schools through the use of integrated evidence-based practices. Although the effects of SWPBIS are well-documented in elementary schools, there is increasing interest in implementing SWPBIS in high schools. SWPBIS has been shown to significantly reduce problem behaviors in high schools, but administrators, staff, and families in high schools often have a broader set of desired outcomes. This evaluation brief investigated the effects of SWPBIS implementation on reported illegal drug and alcohol use in high schools. The specific question examined for this evaluation brief was: to what extent do high schools implementing SWPBIS have lower reported use of illegal drugs and alcohol?