Extensive research has documented the link between exclusionary discipline and numerous detrimental youth outcomes including lower academic achievement, a greater likelihood of being pushed out of school, and an increase in substance use and future criminal justice involvement. To engage in upstream prevention to reduce opioid and other substance misuse among youth there is a need to examine systems-wide, preventative interventions in schools to reduce educators biased and punitive interactions with students while implementing equitable supports. Thus, "Preventing School Exclusion and Opioid Misuse: Effectiveness of the Inclusive Skillbuilding Learning Approach (ISLA)" is being submitted to the National Institutes of Health, through the HEAL Initiative (RFA-DA-23-051). The proposed project aims to evaluate the effectiveness of ISLA, an instructional and restorative alternative to exclusionary discipline, on improving the social determinants of health (SDOH) of education access and quality, and social and community context to prevent school exclusion and opioid and other substance misuse. The investigators will conduct an effectiveness-implementation Hybrid Type 1 clustered randomized controlled trial in 60 middle schools across six states. All students and educators randomized to treatment will receive ISLA, and the investigators will evaluate impacts of ISLA on student outcomes from the end of 6th to the end of 8th grade. In addition, the investigators will incorporate methods to understand intervention processes across multiple levels of the school context. Our first aim is to examine the effectiveness of the ISLA. The investigators will test the direct effects of ISLA on the SDOH of education access and quality, specifically: (a) exclusionary discipline practices (office discipline referrals, in- and out-of-school suspensions, expulsions); (b) student engagement; and (c) inclusive teaching practices. The investigators will also test the direct effects of ISLA on the SDOH of social and community context, specifically: (a) student-teacher relationships; and (b) school climate. Additionally, the investigators will test the direct effects of ISLA on opioid and other substance misuse and associated risk factors. Our second aim is to examine the mediators and moderators of ISLA intervention effects which serve as key mechanisms for change in opioid and other substance misuse and associated risk factors. The investigators will examine the putative mediating effects of ISLA social determinant mechanisms on opioid and other substance misuse and associated risk factors. The investigators will also examine the potential moderating effect between student race/ethnicity and the ISLA intervention on reductions in exclusionary disciplinary practices. Finally, our third aim is to evaluate the implementation outcomes of the ISLA intervention, including: (a) feasibility, usability, acceptability, and fidelity; (b) sustainment; and (c) cost analysis. This project will fill a persistent gap in the field of substance use, by evaluating whether upstream school-based preventative interventions that target and improve SDOH can have meaningful impacts on preventing opioid and other substance misuse and associated risk factors.