This document begins by discussing the important role self-concept plays in a student's academic achievement, social adjustment, and physical capability. A perceptual notion of self-concept is defined as awareness through senses. An operational notion of self-concept is defined as self-descriptive behaviors. Literature is reviewed which defines self-concept and concludes that measurement of different definitions are difficult to perform. Self-concept is then defined as the individual's repertoire of self-descriptive behavior including self-knowledge, self-esteem, and self-ideal which can be measured by physical maturity, peer relations, academic success, and school adaptiveness. The literature on a perceptual model of self-concept and on the operational model are reviewed. Empirical studies on the relationship of self-concept and performance are discussed. References are included. (ABL)