Stephen W. Porges is a Professor in the Department of Psychiatry at the University of North Carolina in Chapel Hill, North Carolina. Prior to moving to North Carolina, Professor Porges directed the Brain-Body Center in the Department of Psychiatry at the University of Illinois at Chicago, where he also held appointments in the Departments of Psychology, BioEngineering, and the Program in Neurosocience. Prior to joining the faculty at the University of Illinois at Chicago, Dr. Porges served as Chair of the Department of Human Development and Director of the Institute for Child Study. He is a former President of the Society for Psychophysiological Research and has been President of the Federation of Behavioral, Psychological and Cognitive Sciences (now called the Federation of Associations in Behavioral & Brain Sciences), a consortium of societies representing approximately 20,000 biobehavioral scientists. He was a recipient of a National Institute of Mental Health Research Scientist Development Award. He has chaired the National Institute of Child Health and Human Development, Maternal and Child Health Research Committee and was a visiting scientist in the National Institute of Child Health and Human Development Laboratory of Comparative Ethology. He was awarded a patent on a methodology to describe neural regulation of the heart. Porges is a neuroscientist with particular interests in understanding the neurobiology of social behavior. His research crosses disciplines and he has published in anesthesiology, critical care medicine, ergonomics, exercise physiology, gerontology, neurology, obstetrics, pediatrics, psychiatry, psychology, space medicine, and substance abuse. In 1994 he proposed the Polyvagal Theory, a theory that links the evolution of the autonomic nervous system to the emergence of social behavior. The theory provides insights into the mechanisms mediating symptoms observed in several behavioral, psychiatric, and physical disorders. The theory has stimulated research and treatments that emphasize the importance of physiological state and behavioral regulation in the expression of several psychiatric disorders including autism and provides a theoretical perspective to study and to treat stress and trauma.