Neural processes that support individual differences in attachment security and affect regulation are currently unclear. Using electroencephalography, we examined whether securely attached individuals, compared with insecure individuals, would show a muted neural response to experimentally manipulated distress. Participants completed a reaction time task that elicits error commission and the error-related negativity (ERN) a neural signal sensitive to error-related distress both before and after a distressing insecurity threat. Despite similar pre-threat levels, secure participants showed a stable ERN, whereas insecure participants showed a post-threat increase in ERN amplitude. These results suggest a neural mechanism that allows securely attached people to regulate distress.