At the time of the first assessment in kindergarten, the mean age of the children was 6.5 years (SD=0.48). Across all sites, the sample was 69 % boys, 51 % African American, 47 % European American, and 2 % of other ethnicity. Families had elevated risk characteristics: 58%were single-parent families, 29 % of the parents had not finished high school, and 40 % were in the lowest socioeconomic class, representing unskilled workers (Hollingshead 1979).
