Examined two hypotheses on the joint effects of 19-month attachment security and child care experience in the second year of life on six cognitive and language measures at 24, 30, and 36 months in a sample of low-income toddlers. Both hypotheses were tested with planned single degree of freedom simple main effect contrasts. The compensatory hypothesis, that center care mitigates the adverse effects of insecure attachment on cognitive and language development of low-income children by providing children with a more stimulating environment than would have been experienced at home with mothers, was supported. However, there was little support for the lost resources hypothesis, that any type of out-of-home care would negatively impact secure children’s language and cognitive development because of the time spent away from a secure mother–child relationship.