Oxytocin (OT) is a neuropeptide associated with parenting and social perception in mammals. Exogenous OT can be safely administered intranasally in humans, enters the brain in high concentrations, increases positive interpersonal and parenting interactions, promotes cooperation and trust, and reduces stress-induced physiological responses. Due to OT's involvement in processes associated with parent-child interactions (e.g. bonding), we hypothesize that the OT system represents a highly promising focus of research into the biological underpinnings of family functioning, as well as a promising target for biological interventions aimed at improving communication between parents and their children with ASD and reducing unhealthy interactions. We will test these hypotheses by exploring the effects of exogenously administered OT to caregivers on parent-child interactions and physiology during a laboratory-based parent-child interaction task. If successful, this would represent the first demonstration of a neurobiological factor in the family functioning of persons with ASD, and would represent the first biological intervention applied to family members of persons with ASD, rather than to the individual with ASD.