A Self-Concept Scale for Adolescents based on Havighurst's Developmental Tasks for Youth was constructed to reflect the adolescents' perceptions of their ability to achieve these tasks in relation to personal abilities, the abilities of others, and the criteria for successful task completion. A validity and reliability study showed the scale to be both valid and reliable. The scale was administered to 256 Indian students at a reservation high school in Arizona. Grade point average (GPA) was the only variable on which a significant difference was obtained in response to the instrument; students with higher GPA's also scored higher on the average than students with lower GPA's. The majority of the students saw themselves as fairly competent persons in terms of the developmental tasks, a finding consistent with a self-esteem study of over 2000 American Indians by Dreyer and Havighurst which found that Indian students who attended predominantly Indian schools judged themselves more positively than Indians who attended predominantly non-Indian schools. (The Self-Concept Scale for Adolescents and a report of the validity and reliability study are included.) (Author/NRB)