Effects are reported of a Durham, North Carolina Education Improvement Program (EIP), a five-year compensatory education program, on social, intellectual, linguistic, and academic development of disadvantaged children. Regarding socialization, changes in social behavior are found to be more a function of specific setting variables, especially teacher behavior, than entry age. The program also reverses the decline in tested IQ after age two in children with no pre-school experience, and it in fact increases his Stanford-Binet score. Although the program does not seem to have different effects on language development in comparison with children in various control groups, it is significantly more effective if continued for two school years or more and when the age of entry is four years. However, in regard to academic performance, the children in the Education Improvement Program are not found to perform as well as children at the end of the first year of primary school. After two or three years of the EIP ungraded primary experience, the EIP pupils on the average score higher than their controls, but the differences are non-significant. (LH)