The senior author of this text, Golder N. Wilson, MD, PhD, is a distinguished professor of pediatric genetics and director of genetics and metabolism at the University of Texas Southwestern Medical Center, Dallas. He has 20 years' experience in directing programs in genetic-metabolic disease and birth defects. The co-author, W. Carl Cooley, MD, medical director of the Crotched Mountain Rehabilitation Center in Greenfield, NH, and associate professor of pediatrics, Dartmouth-Hitchcock Medical Center, also has more than 20 years' experience in directing developmental pediatric programs. Both of these authors have children with disabilities and are active in parent groups directed toward children with disabilities. They are, therefore, in a unique position to write this text from their long professional and personal experiences.