Negative and positive urgency are facets of trait impulsivity that have been identified as possible risk factors for problematic substance use. Relationships between these traits and substance use measures have not yet been widely investigated in adolescents. In the current study, a sample of 270 adolescent students completed self-report measures of impulsivity-related traits, their alcohol and cannabis use, problematic use, and perceived peer use. Zero-inflated negative binomial regression models indicated that both urgency traits accounted for significant variance in problematic alcohol and cannabis use scores, even after accounting for nonurgency impulsivity traits and typical substance consumption. Furthermore, both urgency traits moderated the positive association between perceived peer alcohol use and individual problematic use. Results indicate that the urgency traits show a direct association with problematic substance use in adolescence, and that high urgency adolescents who believe their peers drink high levels of alcohol may be at increased risk of problematic alcohol use.