In a longitudinal study, a group of 41 children from lower class families were examined for differences in child-mother and mother-child attachment patterns at 30 months of age. Twenty-three children had been cared for by their mothers from birth until 30 months of age, and 18 had been enrolled in a day care center for at least 1 year. Data sources were an intensive semistructured interview to rate mother-child interaction, a Home Stimulation Inventory scored on the basis of a home visit, and developmental testing using the Stanford-Binet or Cattell Infant Intelligence Scale. No significant differences in child-mother or mother-child attachment were found between children reared at home and day care children. In respect to child-mother attachment, better developed infants tended to be more positively related to their mothers and came from homes where a high quantity and quality of stimulation was available. It was concluded that infant day care programs can contribute positively to the cognitive, social, and emotional development of the child without harming the child's emotional attachment to the mother. (DR)