<p>Primary prevention interventions represent a promising strategy for addressing rising rates of substance use among adolescents, yet substantial heterogeneity exists in intervention formats, content, goals, outcomes measured, and effectiveness. This scoping review aimed to document primary prevention initiatives targeting adolescent substance use.&#xa0;A systematic search of APA PsycINFO, ERIC, Medline, CINAHL, and SocINDEX was conducted for articles published 2020 onward. Eligible studies examined primary prevention interventions targeting substance use related outcomes among adolescents aged 10-19, were published in English, and were conducted in the United States, Canada, or Australia. Studies focused on treatment or diagnosed substance use disorders were excluded. Two independent reviewers screened articles, and data were charted using a standardized form.&#xa0;The search identified 24,617 records, of which 71 studies met inclusion criteria. Studies varied widely in sample size, design, and intervention characteristics and were conducted primarily in the United States, with additional studies from Australia and followed by Canada. Most interventions were school-based, followed by digital, media-based, community-based, and policy-level approaches, with fewer hospital- and parent-based programs. Interventions most commonly targeted general substance use or e-cigarette use. Many interventions demonstrated improvements in knowledge, attitudes, risk perception, and refusal skills, while effects on substance use behaviours were mixed and varied by intervention type and substance.&#xa0;School-based interventions were prominent and show promise for improving knowledge and attitudes, but evidence for sustained behavioural change is limited. Future research should emphasize long-term outcomes and further evaluate emerging digital and policy-level strategies.</p>