Aggressive behavior among adolescent girls is a growing and serious problem (Office of the Juvenile Justice Dept., 1998), yet the majority of studies of aggressive behavior focus on males. This proposal represents one of the first prospective studies of adolescent girl's aggressive behavior. The overarching goal of this project is to identify individual- and family-level predictors of adolescent girls' aggressive behavior, with particular attention to depression. Results from the proposed study will not only deepen our understanding of these problems but may also facilitate treatment efforts by targeting girls at-risk of engaging in aggressive acts. The proposed two-year project includes three central aims: 1) to investigate whether previously hypothesized individual-level precursors are associated with the development of aggressive behavior in girls; la) to determine whether girls' engagement in aggressive acts typically precedes or follows the emergence of depressive symptoms; 2) to predict whether previously hypothesized family-level precursors are associated with development of girls' aggressive behavior and whether family-level characteristics moderate the relationship between individual level risk factors and girls' aggressive acts; and 3) to determine whether a cumulative risk model describes the relationships between girls' engagement in aggressive acts and the number of individual- and family-level risk factors experienced. Data will be drawn from the first three waves of the Project on Human Development in Chicago Neighborhoods (PHDCN, P.I., F. Earls). At the writing of this proposal, wave I data is being analyzed and results reported, wave 2 data is being cleaned, and wave 3 data is being collected. Respondent retention between waves one and two was 86.2 percent. The initial sample includes 1, 1 1 1 9-, 12-, and 15-year old adolescent girls from African American, Latino, and white families living across 74 neighborhoods. The proposed study uses Hierarchical Linear Modeling (BLM) to examine the hypothesized relationships. Preliminary results of the cross-sectional data showed a consistent relationship between girls' engagement in aggressive acts and depressive symptoms, even after controlling for other important variables (e.g., substance abuse, family aggression). Further, results showed that early maturing girls are at elevated risk for engaging in aggressive acts.