Early childhood, middle childhood, and early adolescence determinants of functional literacy in adulthood are investigated, using 20-year longitudinal data from a sample of black children of teenaged mothers from the Baltimore metropolitan area. Document literacy was assessed by a test that consisted of a subset of items of the National Assessment of Educational Progress (NAEP) adult literacy test. The Baltimore sample is compared to the NAEP sample. Family environmental factors, early childhood developmental level, and educational career factors were considered as predictors of young adulthood literacy. Preschool cognitive and behavioral functioning is highly predictive of literacy in young adulthood, even when the effects of family environmental characteristics, including living arrangements, the quality of the home environment, maternal education, and income, are controlled. Grade failure in elementary school is also associated with literacy, but this effect disappears when the measure of preschool abilities is controlled. Family environmental factors that are predictive of literacy include maternal education, family size in early childhood, maternal marital status, and income in middle childhood and early adolescence. Policy implications of these findings are discussed.