Research testing Moffitt’s taxonomy of antisocial behavior has concentrated on life-course-persistent (LCP) as opposed to adolescence-limited (AL) offending. For Moffet, LCP adolescents are comprised of mostly male offenders whose antisocial behavior originates early in life, AL delinquency occurs near puberty as a function of factors endemic to the peer social contest of adolescence. This includes the realization that adolescents are physically mature enough to engage in adult-like behaviors, but are forbidden to engage in such acts because of their biological age. Data drawn from the 1996 Youth in Transition (YIT) survey were used. Personal interview and questionnaire data were obtained from 2,213 male youths as they were entering their sophomore year in high school. The second wave of data was collected from 1,886 respondents in the spring of their junior year in high school. Findings indicated that AL delinquency was characterized by involvement in rebellious but not aggressive delinquency. Further, rebellious delinquency was accounted for by the interaction between early maturity and the autonomy aspects of peer activities. These results pointed toward the continued examination of biological age in the context of physical maturity and its relation to delinquency. They were consistent with the view that biological rather than chronological age was the more salient marker for delinquency. The dramatic increase of testosterone levels for males not only mimics the increase of delinquency prevalence observed in the age-crime curve, but it has also been found to be related to delinquency. Four important future research efforts should be to consider gender differences; examine the pubertal changes in relation to delinquency rates; examine interactions between maturity and delinquent peers; and explore issues concerning whether adolescent offenders will desist as adulthood approaches. 4 tables, 9 notes, and 45 references