The relationship between grade point average, grade level, age, sex, social class, and self-concept as defined by Havighurst's Developmental Tasks for Youth was investigated. Subjects were 280 adolescents ranging in age from 13 through 18 and coming from a variety of social classes. Each subject completed a Self-Concept Scale for Adolescents, designed to measure how adolescents view their abilities to perform tasks in relation to: what they are able to do; what others do; and what it takes to be successful at the task. Results indicate that social class is significantly related to personal perceptions of abilities, and that low achievers perceive themselves as less able than high achievers to complete developmental tasks. Sample items from the Self-Concept Scale for Adolescents and the validation data for this scale are provided in the appendix. (Author/HLM)