Youths growing up in disadvantaged families are at risk of experiencing behavioral and psychological problems and may respond less well to therapeutic interventions than those who are from more favorable backgrounds. Additionally, the experience of mental health or substance-related difficulties in adolescence, can impact educational attainement and adult socioeoconomic standing. To illustrate the complex relation between socioeconomic position and mental health and substance use, this symposium will rely on four presentations. First, data from France will show the elevated levels of behavioral and psychological difficulties in youths growing up homeless. Second, a study based in the Netherlands, will show that the efficacy of Youth Initiated Mentoring varies depending on background socioeconomic circumstances. Finally, data from the longitudinal TEMPO study based in France will show that cannabis use in adolescence is a cause of educational failure and that the experience of food insecurity is tightly related to mental health and substance use problems in young adults. Overall, this symposium will show that the relationship between socioeconomic factors and mental health in youth is bidirectional, and research in this area should be taken into account in the design of interventions aimed at supporting high-risk and community youths.