The study found that parental support and trajectories of depressive symptomatology interacted with one another in a reciprocally interactive fashion. Adolescents' perceptions of parental support influenced their depressive symptoms. In turn, this influenced their perceptions of parental support in young adulthood. Regarding gender as a factor, adolescent girls who reported low levels of parental support began the study period with a significantly higher level of depressive symptoms than adolescent boys who reported similarly low levels of parental support. This provides additional support for the argument that girls are more psychologically reactive than boys to the quality of their relationships. Adolescent depression, however, apparently had an equally detrimental effect on perceptions of parental support among young adult women and men. This suggests that all parents, not just parents of adolescent girls, could benefit from learning how to identify symptoms of depression in their children and where to go for appropriate treatment. Since this is the first study to use developmental modeling techniques to evaluate the reciprocal relationship between parental support and trajectories of depressive symptomatology across the transition from adolescence to young adulthood, these results are preliminary. More research is needed to provide a fuller understanding of the dynamic nature of the relationship between social support and psychological well-being. The study applied latent growth curve analysis to data from 3 waves of the National Longitudinal Study of Adolescent Health (n=10,828). At Wave 1, the mean age of respondents was 15.28; and at Wave 3, the mean age of respondents was 21.65. The in-home surveys included questions about physical and mental health, health-related behaviors, academic functioning, and relationships with family and peer-group members. 9 tables, 1 figure, and 43 references