Most behavioral models examine adolescent health risk behaviors using a reflective, deliberate social-psychological framework. In this study, adolescent cannabis use is investigated via an expanded social-psychological model of behavioral decision-making: the Theory of Planned Behavior (TPB). The aim was to examine the contribution of nondeliberative (impulsivity), developmental (perceived parenting styles), and temperamental (moral norms, mental health, delinquency) factors in adolescent cannabis use. A longitudinal questionnaire with baseline and follow-up measurement (14-day interval) was used. Participants were Sixth Form College students (n = 199) aged 16-18 (mean age = 16.44, SD = -0.55). At baseline (T1), demographics, TPB variables, and additional socio-psychological variables were measured. Fourteen days later (T2) self-reported cannabis use was measured. Logistic regression analyses indicated that the impulsivity subcomponent of lack of premeditation and moral norms predicted self-reported cannabis use behavior. Perceived parental rejection predicted cannabis use intentions. Adolescent cannabis use can be better understood through the expanding of behavioral models to account for nondeliberative, developmental, and temperamental factors. Drug education interventions should aim at developing self-instruction training programs teaching adolescents effortful thinking while family-based interventions should focus on encouraging open parent-adolescent communication which has shown to influence adolescents’ cannabis use.