<p>Adolescent alcohol and tobacco use are associated with various health risks, including cognitive and developmental impairments. Minority youth may face additional vulnerabilities, such as racism and discrimination, which contribute to stress and an increased risk of substance use. This study examined the effects of a school-based prevention program implemented by the Brazilian state-level police forces in schools, focusing on differences across racial groups. We analyzed data from two cluster-randomized controlled trials conducted in 2019 in public schools on the outskirts of São Paulo. The sample included fifth- and seventh-grade students and assessed the effectiveness of the PROERD program in preventing alcohol and tobacco use across racial groups. Racial classification was based on self-identification and categorized according to the official Brazilian census: White (<i>branca</i>), Black (including <i>preta</i> and <i>parda</i>), and Others (Indigenous people, Asians, and their descendants). After nine months, Black seventh-grade students had a higher risk of initiating alcohol and tobacco use compared to their White counterparts. We found no significant preventive effect on alcohol or tobacco use in any racial group within any given grade level. The findings underscore the need for more comprehensive, culturally sensitive prevention strategies that address the specific risk factors affecting racial minority adolescents and promote greater health equity.</p>