The first in a series of related reports (see TM 000 775), this paper attempts to define a concept of psychosocial maturity which would be appropriate as a comprehensive educational goal. Biological, sociological, psychological and temporal formulations of maturity are discussed and compared. Am interdisciplinary model of maturity is evolved which emphasizes (1) effective individual functioning, (2) effective interpersonal relationships, and (3) system maintenance. Effective individual functioning requires information necessary for the individual to grow and to maintain himself in the "average expectable environment" and work-related skills and motives necessary for the same end. Effective interpersonal relationships are a function of predictability and trust, and they contribute to the survival of society, which is the concern of sociological models of maturity. System maintenance depends on reproduction, socialization of the young, and shared values. Psychological standards of maturity involve the development of favorable attitudes toward self, others, and work; and of a behavior-guiding system of values. These criteria are embedded in the content of the three categories. Maturity is discussed in relation to current developments in schools and applications of a potential maturity scale are suggested. (Author/AG)