The Haifa Study of Early Child Care recruited a large-scale sample (N = 758) that represented the full SES spectrum in Israel, to examine the unique contribution of various child-care-related correlates to infant attachment. After controlling for other potential contributing variables--including mother characteristics, mother-child interaction, mother-father relationship, infant characteristics and development, and the environment--this study found that center-care, in and of itself, adversely increased the likelihood of infants developing insecure attachment to their mothers as compared with infants who were either in maternal care, individual nonparental care with a relative, individual nonparental care with a paid caregiver, or family day-care. The results suggest that it is the poor quality of center-care and the high infant-caregiver ratio that accounted for this increased level of attachment insecurity among center-care infants.