This study examined early observed parenting and child-care experiences in relation to functioning of the hypothalamic-pituitary-adrenocortical axis over the long term. Consistent with the attenuation hypothesis, individuals (n = 863) who experienced: (a) higher levels of maternal insensitivity and (b) more time in child-care centers in the first 3 years of life had lower awakening cortisol levels at age 15. Associations were small in magnitude. Nonetheless, results were (a) additive in that both higher levels of maternal insensitivity and more experience with center-based care uniquely (but not interactively) predicted lower awakening cortisol, (b) not accounted for by later caregiving experiences measured concurrently with awakening cortisol at age 15 or by early demographic variables, and (c) not moderated by sex or by difficult temperament.