Early institutional-deprivation has been found to increase risk for inattention/hyperactivity (ADHD). Notably, studies suggest that children with a history of adversity evidencing an enhanced ERP (the error-related-negativity; ERN) may be protected against attention problems. However, such protective effects of the ERN have been studied in children whom typically experienced residential instability. It is unknown whether error-monitoring is similarly protective for children with stable post-deprivation placements. The present study examined the protective effect of the ERN in a sample of children who experienced at least 3-years of stable, relatively enriched caregiving after being internationally-adopted as infants/toddlers from institutional-care. We included two groups of children adopted internationally before age three, one group adopted from institutional-care (PI:n = 80) and one comparison group adopted from foster-care (FC;n = 44). A second comparison group consisted of non-adopted children (NA;n = 48) from demographically comparable families. At five-years of age, we assessed child ADHD symptoms (parent-report) and behavioral performance and neural correlates of error-monitoring (Go/No-Go task). PI children displayed lower Go/No-Go accuracy relative to FC children, and higher levels of ADHD symptoms relative to NA controls. In both FC and PI groups, longer duration of pre-adoptive out-of-home placement was associated with inattention, especially for children with deficits in error-monitoring. Enhancing cognitive control in the form of error monitoring might be a useful intervention target to protect children from some of the negative outcomes associated with adverse early care. Furthermore, results underscore that regardless of type of pre-adoptive care, we should aim to place children in stable/permanent homes as early as possible.