Purpose: The purpose of this study was to describe the physical activity behavior of high school students living in the Appalachian region of Ohio. Methods: A cross-sectional sample of 1,024 subjects from 11 schools in Appalachian Ohio was drawn. Previously validated instruments were used to measure physical activity behavior over 7 days. Findings: Appalachian adolescents fell short of recommended levels of activity. They reported high rates of sedentary behavior by 9th grade. Appalachian adolescents may be acquiring sedentary behaviors earlier than adolescents living in other regions. Low rates of activity make this population particularly at risk for the health consequences associated with inactivity.