Project Summary/AbstractDepression among adolescents is a major concern in the United States (U.S.). It is estimated that theprevalence of depression among those 12 to 17 years old was 12.5% or 3 million in 2015.5 This represents aserious public health issue as adolescents who are depressed have an increased risk of comorbid psychiatricdisorders, suicide, and substance abuse compared to adolescents who are not depressed. Few studies haveexamined the role of neighborhoods on depression, especially among adolescents. To address this gap, thissecondary data analysis study of a representative sample of U.S. adolescents proposes to (1) determine theassociation between adolescent-perceived collective efficacy and depressive symptoms among U.S.adolescents at baseline, (2) examine the moderating role of adolescent-perceived collective efficacy andparental-perceived collective efficacy on the association between neighborhood structural disadvantage andlevels of depressive symptoms among U.S. adolescents at baseline, separately, and (3) estimate the changetrajectories in the relationship between depressive symptoms and in neighborhood structural disadvantageamong U.S. adolescents at baseline, one year later, and eight years later. The central hypothesis is thatneighborhood structural disadvantage and collective efficacy will affect depressive symptoms amongadolescents, partially explaining the increase in depression among U.S. adolescents. The proposed study willuse 8 years of data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), alongitudinal study comprised of U.S. adolescents in grades 7–12. The total sample size is 24,210 withadolescents and their parents representing various racial/ethnic groups. Multilevel modeling will be used todetermine the effect of neighborhood structural disadvantage and collective efficacy on depressive symptoms.The findings from the proposed study would help in the identification of neighborhood characteristics thatimpact depressive symptoms and subsequently depression incidence among adolescents in the U.S.Components of neighborhood structural disadvantage and collective efficacy would serve as targets for thedevelopment of structural and other intervention strategies such as community-level interventions, aimed atreducing or preventing depression. Ultimately, addressing neighborhood structural disadvantage and improvingcollective efficacy may help to reduce depressive symptoms and increase mental health utilization amongadolescents, thereby reducing the growing mental health burden among youth.