Studies examining neighborhood effects on adolescent outcomes have indicated that adolescents growing up in low-income neighborhoods are at higher risk of developing internalizing and externalizing behaviors. However, knowledge of the long-term effects of neighborhood disadvantages on internalizing and externalizing behaviors and the involved mechanisms across adolescence is limited. Using family life course theory and the cumulative advantage/disadvantage perspective, this study examined how community disadvantages in early adolescence accumulate over time to influence later internalizing and externalizing behaviors and the protective effects of subjective appraisals of social support by adolescents and their primary caregivers. I estimated a two-level growth curve model using three waves of data from the Project on Human Development in Chicago Neighborhoods (PHDCN). Results indicated subjective appraisals of social support by both adolescents and caregivers played a protective role to buffer the negative effects of community disadvantages on internalizing and externalizing behaviors across adolescence. These results provide insight for the development of intervention programs at both family and government levels to improve adolescent outcomes. / Ph. D.