A longitudinal study was made of women and their first-born children who have different employment and day care experiences during the child's first three years of life. Specific aims of the study were (1) to gain full account of the history and experience of women who return to full-time employment while their first child is still young and of their children who receive non-parental day care from an early age; (2) to assess the consequences, in terms of the well-being of the woman and child, of full-time maternal employment and non-parental day care when both are initiated at an early age; and (3) to consider how far and in what ways these consequences are influenced by certain mediating factors, including the type and stability of non-parental day care, and the characteristics of the children, including gender and temperament. The study involved 255 women and their children. Four groups were compared: unemployed women not using day care and women who were employed full-time and who used relatives, childminders, or nurseries. Data were collected when children were 5, 10, 18, and 36 months of age. This paper reports and discusses data on socio-emotional development collected at the third contact during home visits involving multiple measures. (RH)