Participants in this multi-cohort longitudinal study were enrolled at ages 10 – 12 years. This report included data on the 387 youth who completed the first of four planned annual assessments. Seventy percent of the subjects attended 7 Philadelphia schools where onsite enrollment occurred. The remaining 30% attended other Philadelphia area schools and were recruited through flyers distributed at schools and posted in local venues such as libraries. Parental consent and youth assent were obtained in accordance with the protocol that was approved by the IRB of the Children’s Hospital of Philadelphia. Youth were reimbursed for their time and travel.
