Earlier research has associated early puberty with emotional and behavioral symptoms particularly among girls, while among boys, findings have been contradictory as to whether risks are associated with early or late pubertal timing. The authors studied the association between pubertal timing and substance use behaviors in middle adolescence in a 2-year follow up study of 2,070 (mean age 15.5 years, SD 0.36; 56.4 percent females) Finnish adolescents. Pubertal timing was measured by age at menarche/oigarche. Eleven years or less was classified as early, 12-13 years as normative and 14 years or later as late pubertal timing. Substance use behaviors were elicited by a number of questions related to alcohol use patterns, smoking and cannabis use. As factors that could explain the association between pubertal timing and substance use, the authors studied depressive symptoms, delinquency and aggression, and parental monitoring. In boys, all these substance use behaviors were the more common the earlier the puberty and the associations persisted at age 17. Among girls, early pubertal timing was similarly associated with substance use behaviors at age 15, but no longer at age 17. The associations between pubertal timing and substance use behaviors persisted when symptom dimensions and parental monitoring were added into the models. Early puberty is a risk factor for substance use particularly among boys. Among girls, the impact of pubertal timing already tempers off during adolescence. (Published Abstract)