OBJECTIVE This study investigates the levels and rates of growth of conduct problem behaviors over time in an urban sample of American youth. Our hypotheses focused on differences between the sexes and between youths with and those without early use of alcohol without parental permission. METHODS Data for this study are from an ongoing epidemiologic study of urban public school students, recruited originally at the time of their entry into Grades 1-2 between 1985 and 1987. Each spring, from 1991 to 1993, a total of 1,212 students were interviewed privately for this study. A total of 408 (54.2% female, 84.7% black) respondents met study criteria as either an "early unsanctioned alcohol user" or an "abstainer." These youths constitute the analytic subsample. RESULTS Estimates from longitudinal growth modeling analyses showed that boys and girls had different initial levels of conduct problem behaviors, but similar rates of growth. Both the initial level of conduct problem behaviors and the rates of growth were greater for early unsanctioned alcohol users as compared to abstainers. In a combined analysis the difference between early unsanctioned alcohol users and abstainers seemed to offset the initially observed sex difference. CONCLUSIONS Early alcohol use without parental permission was associated with higher levels of conduct problem behaviors by the ages of 10-12 years and higher rates of growth in those behaviors during the transition from late childhood to early adolescence for both boys and girls, although the levels differed by sex. It may be that unsanctioned early alcohol use puts youths on an accelerated pathway of conduct problem behaviors and development of conduct disorder in adolescence.