To examine effects of ethnicity, SES, and residence on students' participation in formal clubs, activities, and sports, a survey was administered to 1,450 students at a county-wide consolidated high school in southern Appalachia. The purpose was to investigate the significance of Appalachian ethnicity as an explanation for behavior and to understand factors influencing internal social structure in high schools. The survey included three general sections. The first elicited background information to establish students' family ties to Appalachia, SES, and residence; the second elicited information concerning past and present participation in high school clubs, etc.; the third asked questions about employment, after-school work at home, and transportation. Participation in various activities was then compared separately with SES, residence, and ethnicity. All of the variables of SES, residence, and Appalachian ethnicity showed significant relationships to the level of participation and the type of participation. Students who were Appalachian, rural, and from the lower socioeconomic class participated in clubs, activities, and sports significantly less than did non-Appalachian students who resided in town and were from the middle or upper socioeconomic class. Residence and SES strongly mediated the influence of ethnicity; higher SES and town residence appeared to overcome the liabilities of being Appalachian. (CHG)