The study found that adolescent boys who experienced more family transitions tended to experience more changes in problematic peer interactions and were more likely to engage in higher levels of delinquency over time. The findings were similar for the models that predicted drug use, except that some of the Wave 6 variables had direct effects on delinquent outcomes for both boys and girls, but did not mediate the effects of family transitions. The effect of family transitions was mediated only partially by an increase in changes in problematic peer interactions for adolescent boys, as the direct effect of family transitions remained statistically significant even after the introduction of the mediating variables. This suggests that other variables may mediate the impact of family transitions on delinquency. Adolescent boys who experienced more changes in family structure over the 1.5-year period were more likely to increase their drug use over time as both a direct result of these changes and indirectly as these transitions shaped their interactions with peers. Adolescents who experienced an increase in school problems (boys only) and negative peer influences (both boys and girls) over time were also involved in more delinquency. In addition, family and school problems, along with peer interactions (both boys and girls) were associated with increased drug use over time. Despite the differences noted between boys and girls, however, a comparison of the coefficients in the models showed no statistically significant differences between boys and girls. The number of transition types examined (n=14) precluded making statistically meaningful comparisons of the impact of different types of family transitions. 6 tables, 1 appendix, and 52 references