Prevalence of problematic cannabis use in detained youth is high and is related to various serious issues such as mental and physical health problems and recidivism. Therefore it is important to provide effective interventions to reduce problematic cannabis use. However, traditional interventions for substance use seem ineffective for this specific population, expectedly due to population characteristics and treatment setting in detention. This study aims to provide insight on underlying mechanisms of problematic cannabis use of this population to inform future interventions. The study proposes a relationship between hopelessness and problematic cannabis use, which is mediated by attentional bias towards cannabis use. Finally it proposes that the relationship between attentional bias and cannabis use is moderated by executive control. Understanding the possible role of these factors for problematic cannabis use, can be useful to inform interventions on what to focus on.