Young children living in institutional settings often show a range of deficits in social, physical, and cognitive functioning. Whereas the diurnal production of cortisol has been examined among post-institutionalized children in a number of investigations, studies of children continuing to live in institutions are limited. In this study, we assessed wake-up and bedtime cortisol among 73 children living in Russia, with 52 institutionally-reared (n = 31 at time 2), and 21 family-reared (n = 18 at time 2). Institutionally-reared children showed a blunter wake-up to bedtime slope than family-reared children at both time 1 and time 2, with significantly higher cortisol levels at bedtime. These findings highlight the deleterious effects of institutional care on children's developing neuroendocrine regulation.