Children raised in chaotic households show affect dysregulation during later childhood. To understand why, we took day-long home recordings using microphones and autonomic monitors from 74 12-month-old infant-caregiver dyads (40% male, 60% white, data collected between 2018 and 2021). Caregivers in low-Confusion Hubbub And Order Scale (chaos) households responded to negative affect infant vocalizations by changing their own arousal and vocalizing in response; but high-chaos caregivers did not, whereas infants in low-chaos households consistently produced clusters of negative vocalizations around peaks in their own arousal, high-chaos infants did not. Their negative vocalizations were less tied to their own underlying arousal. Our data indicate that, in chaotic households, both communicating and responding are atypical: infants are not expressing their levels of arousal, and caregivers are under-responsive to their infants' behavioral signals.