This document provides a bilingual (English and French) report on the Turkish Early Enrichment Project, a four-year longitudinal study of the impact of educational day care combined with mother training on child development. This comprehensive approach was compared with custodial day care and home care, both with and without home intervention. The study was conducted in five low-income areas of Istanbul. Six day care centers attached to factories were chosen, three providing only custodial care and three providing preschool education. The study began with a sample of 280 children, including all three- and five-year-olds in the educational centers, a similar number from the custodial centers, and a group of children who were not in day care centers. Multiple assessments measured children's cognitive, personality, and social development; family context; and day care context. It was found that test scores in intelligence and analytical ability of children whose mothers underwent training differed significantly from those of children whose mothers were not trained. Children at home and children in custodial centers benefitted the most from mother training. Children in educational day care whose mothers had been trained had the highest scores on almost every cognitive development measure. Mother training began to affect children's grades after only one year. Mother training had positive effects on the socioemotional development of the children, on mother-child interaction, and on the mothers' role and status in the family. (AC)