Objectives. We examined whether kindergarten teachers' ratings of children's prosocial skills, an indicator of noncognitive ability at school entry, predict key adolescent and adult outcomes. Our goal was to determine unique associations over and above other important child, family, and contextual characteristics. Methods. Data came from the Fast Track study of low-socioeconomic status neighborhoods in 3 cities and 1 rural setting. We assessed associations between measured outcomes in kindergarten and outcomes 13 to 19 years later (1991-2000). Models included numerous control variables representing characteristics of the child, family, and context, enabling us to explore the unique contributions among predictors. Results. We found statistically significant associations between measured social-emotional skills in kindergarten and key young adult outcomes across multiple domains of education, employment, criminal activity, substance use, and mental health. Conclusions. A kindergarten measure of social-emotional skills may be useful for assessing whether children are at risk for deficits in noncognitive skills later in life and, thus, help identify those in need of early intervention. These results demonstrate the relevance of noncognitive skills in development for personal and public health outcomes. (author abstract)