Forty-one subjects who score at the high and low extremes of the Psychosocial Maturity (PSM) Inventory were intensively interviewed. These interview data were analyzed to contrast the phenomenological and psychodynamic forces in the lives of these subjects that influence their current state of psychosocial maturity. Case material is presented. Discussion focuses on the interplay between the processes of adolescent ego development and the traits of psychosocial maturity. The growth of impulse control, increases in self esteem and gains in autonomy are all found to contribute to greater maturity. Heterosexual behavior, by contrast, bears a more complex relationship to psychosocial maturity in adolescence. Implications for theory are discussed with respect to psychoanalytic and Eriksonian literature. (Author)