Adolescence is a period of heightened vulnerability to depression and increased flux in interpersonal relationships. Interpersonal stress is one of the strongest predictors of adolescent depression. Interpersonal stressors involving targeted rejection and humiliation, in which an individual is rejected and their social status is threatened, are especially potent predictors of depression in adults. However, there are several gaps in our understanding of the impact of targeted rejection/humiliation on adolescents’ depressed mood. First, we lack knowledge of important descriptive information about the nature of these events in daily life during adolescence, including their frequency, severity, and with whom they occur. Second, it is unknown how targeted rejection/humiliation experiences affect momentary change in depressed mood as compared to long-term change in depression symptoms. Third, age and gender differences in momentary responses to targeted rejection/humiliation remain underexplored. Ecological momentary assessment (EMA) is an ideal methodology with which to examine these questions about adolescents’ momentary and longitudinal changes in depressed mood and depression symptoms in response to targeted rejection/humiliation in the flow of daily life. The proposed study will use EMA in a longitudinal design to (1) descriptively characterize adolescents’ targeted rejection/humiliation experiences in peer and parent-child relationships; (2) examine how targeted rejection/humiliation in these relationships differentially predicts momentary and longitudinal change in depressed mood and symptoms relative to other forms of interpersonal and non-interpersonal stressors; and (3) investigate age and gender differences in targeted rejection/humiliation, and whether age and gender interact with these experiences to predict momentary and longitudinal change in depressed mood and symptoms. Adolescents (N=180) will complete measures of depression and stressful life events at a baseline visit, followed by a 9-day EMA protocol assessing experience of interpersonal stressors and depressed mood; participants will repeat both the baseline visit and EMA protocol at a 6-month follow-up. It is hypothesized that targeted rejection/humiliation will predict momentary and longitudinal increases in depressed mood and symptoms. By using EMA methods and sophisticated analyses, results from the proposed project will address longstanding theoretical issues of adolescence as a period of “storm and stress,” and identify targets for more effective depression prevention and intervention. The hands-on experience gained through this project and training plan will advance the development of the applicant as an independent scientist who investigates how the experience of interpersonal stress contributes to the development and maintenance of internalizing problems during adolescence. The execution of this study, combined with the training activities and consultation with collaborato...