The authors explain that although there is a long held understanding that age and delinquent peers influence delinquent behavior, there is little knowledge concerning how these factors interact to produce delinquent behavior. How age is linked to delinquent behavior remains relatively unstudied and researchers disagree about whether delinquent peer associations precede delinquency or vice versa. Thus, the authors set out to examine the interrelationship of these three factors by studying data from the National Youth Survey (NYS). This survey collected data from youths in three different waves in order to capture changes in delinquent behavior over time. The hypotheses under examination were that first, there would be an interaction between age and delinquent peer associations on delinquency, with delinquent peer associations exerting greater influence over older youths. Second, the authors hypothesized that the relationship between age and delinquent peer associations would be strongest for substance abuse offenses. The findings revealed mixed support for the two hypotheses. The authors did find an interactive relationship between age and delinquent peer associations, but only for some offenses. Further, older youths were not necessarily more influenced by their peer associations. Finally, clear evidence did support the hypothesis that delinquent peer associations would have the greatest influence for substance abuse offenses. In conclusion, the authors suggest that future research should focus on theoretically specifying the relationship between age and peer associations on specific types of delinquency. Tables, references