We used data from a school-based study of 496 adolescent girls to identify qualitatively distinct substance use and substance abuse developmental trajectory groups and tested whether the problematic groups differed from the non-problematic groups on baseline and outcome validation variables. Results identified four substance use groups (late users, normative users, late-heavy users, early-heavy users) and four substance abuse groups (non-abusers, moderate-escalating abusers, moderate decreasing abusers, adolescent-limited heavy abusers). Problematic substance use and abuse trajectory groups, relative to non-problematic groups, showed elevations in baseline validation variables (age 14 delinquency, depressive symptoms, negative affectivity, parental support deficits, body dissatisfaction) and outcome validation variables (age 20 delinquency, depressive symptoms, social impairment, legal problems, school dropout, and substance abuse diagnosis), providing partial validation of this trajectory model. (Contains 6 tables and 2 figures.)