The role of early child care experiences on the development of the mother--child attachment relationship has been studied extensively. However, no prospective studies of early child care have addressed how these experiences might be reflected in the content of attachment representations during adolescence and beyond. The goal of this study was to estimate relatively precise associations between child care quality, child care quantity, and type of care in the first 54 months of life and the content of adolescents' attachment representations around age 18 years (N = 857; 51% female; 78% White, non-Hispanic; mean income-to-needs ratio = 4.13), leveraging data from the longitudinal National Institute of Child Health and Human Development (NICHD) study of Early Child Care and Youth Development. We identified a small positive association between the observed quality of early child care (but not quantity or type of care) and secure attachment states of mind as measured by the Adult Attachment Interview (but not the Attachment Script Assessment) at age 18 years that was robust to demographic covariates and observations of maternal and paternal sensitivity during childhood. We observed no significant interactions among child care variables. Associations between early child care experiences and indicators of adolescent attachment were likewise not moderated by maternal sensitivity from infancy to midadolescence or by maternal reports of child temperament in early childhood.