This Annals volume showcases research presented at the 2012 Association for Research in Nervous and Mental Disease (ARNMD) conference entitled “Childhood Onset Developmental Disorders.” Each paper addresses the unique developmental determinants in the expression and course of highly prevalent conditions in children and adolescents, including anxiety disorders, autism spectrum disorders, and pediatric neurological conditions. Specifically, the papers focus on how basic developmental neuroscience and animal models inform our understanding of these conditions. The topics covered include the psychobiology and treatment of anxiety, the role of anxiety in youth suicide, fear learning, behavioral treatment of autism, the developmental aspects of epilepsy, neurological conversion disorder, pediatric movement disorders (including tics and stereotypies), and the evolving nature of the treatment of tic disorders.