<p>Engaging parents in substance and alcohol use prevention programs could play a key role in delaying the onset of use among adolescents. This research analyzes parents’ perceptions of substance use prevention programs (tobacco, marijuana, vaping, and alcohol) implemented in private schools in the northern area of Santiago, Chile. Using a qualitative design, we conducted 15 semi-structured interviews with parents of adolescents attending four private schools. Our findings reveal limited parental knowledge and understanding of the risks of adolescent substance use and prevention or harm reduction strategies. Most interviewees approach prevention through monitoring and control of their children. They suggest incorporating government prevention strategies into private schools. Our findings underscore the importance of including families in the design of adolescent substance use prevention programs and highlight the urgent need to implement such strategies in private schools.</p>