The purpose of this study is to evaluate the utility of providing comprehensive literacy instruction to preschool children starting at age three. The literacy development in two groups of four-year-old children (N = 1320) was compared during their enrollment in a literacy-enriched Head Start program. The first group entered the program at age four and participated in the program for only one year (Group 4-1); the second group had previously participated in the program at age three and at the time of the study were in their second year of the program (Group 4-2). (author abstract)