The PNC initiative focuses on characterizing brain and behavior interaction with genetics. It includes a population-based sample of approximately 9,500 individuals from the greater Philadelphia area, ages 8-21 years who received medical care at the Children’s Hospital of Philadelphia (CHOP) network. The participants presented for diverse medical conditions, ranging from a well child visit and minor problems to chronic condition management to potentially life threatening health problems, but not ascertained through psychiatric services. They were initially enrolled in the genetic study at CHOP’s Center for Applied Genomics (CAG). Upon assent or consent, participants were genotyped during the time of their clinical visit and provided written permission to be recontacted for studies of complex pediatric disorders. The PNC participants were selected at random after stratification by sex, age and ethnicity, and a total of 1,445 participants also received neuroimaging.