Objective: Adolescent participation in risky and addictive behaviours, such as smoking, substance use, and gambling has the potential to lead to many serious problems. The presence of conduct problems (CPs) and early initiation into risky and addictive behaviours have been independently shown to be associated with adolescent and young adult smoking, drinking, and gambling. Nevertheless, the relation between early initiation into risky and addictive behaviours and CPs remains to be explored among pre-adolescents. Our study aims to examine the prospective relation between CPs in early primary school and pre-adolescent initiation into smoking, alcohol use, and gambling. Method: Our study used data from participants in an ongoing prospective, longitudinal study at the Universite de Sherbrooke to examine cigarette, alcohol, and gambling initiation among primary school-aged boys and girls with CPs. Children were recruited between the ages of 6 and 9 years from several low socioeconomic status public schools in diverse geographical regions of Quebec. Initiation into cigarettes, alcohol, and gambling was measured 1 year later. Results: Children with CPs were found to be at greater risk for early initiation into smoking, alcohol, and gambling. These effects remained even once other known risk factors, such as poor parental supervision and child effortful control, were controlled for. Conclusions: These results suggest that CPs present in early elementary school can predict early initiation in to potentially addictive behaviours among boys and girls. Implications for targeted preventive intervention are discussed.