The chief goal of this study is to examine the relationships among mental health, identity and career development during the transition from adolescence to adulthood and determine whether successful adjustment in emerging adulthood depends on developmental trajectories in the above domains during adolescence. The study proposes to add to our understanding of the risk and protective factors of mental health. It is hypothesized that the emerging sense of personal, ethnic, and national identity and career preparation during adolescence protects young adults form developing internalizing and externalizing problem behavior and buffers the potentially harmful effects of negative life events. Preliminary studies suggest that identity formation and career development are positively related to psychological well-being and negatively to distress, drug and alcohol abuse, and delinquency. There is some evidence that those relationships become stronger as adolescents move into adulthood. This study will examine the patterns of change in and interactions among overall mental health and its components and individual, national, and ethnic identity and career development from adolescence through young adulthood. The participants in this study will comprise a highly diverse sample representative of both sexes as well as ethnic minority, majority, and mixed individuals and a broad range of socio-economic status groups, who will be recruited from the participants in an ongoing study of adolescent development. Thus, the previously collected data will be used as a baseline, which will allow for studying long-term relationships and lagged effects. The study will utilize a longitudinal design with four waves of data collection throughout the first half of the third decade of life. Data analyses will focus on causal modeling in order to determine the direction of the effects as well as change over time and in relation to the normative transitions of emerging adulthood.