75 infants (mean age 15 months) were observed 3 times in the Strange Situation with their professional caregivers, mothers, and fathers. Sensitivity of these attachment figures to the infant's signals during free play, as well as a number of day-care characteristics, were assessed. Attachment classification distribution of infant-caregiver dyads did not differ significantly from infant-mother or infant-father attachment classification distributions. The quality of infant-caregiver attachment was independent of both infant-mother and infant-father attachments. About 10% of the infants had 3 insecure attachments. Professional caregivers observed with more than 1 infant did not have similar types of attachment classifications to all infants with whom they were observed. Infants who were securely attached to their professional caregivers spent more hours per week in day-care, and came from a middle-class background. Their caregivers appeared to be younger and more sensitive during free play than caregivers with whom the infants developed an insecure relationship.