SONSTROEM, R. J. and W. P. MORGAN. Exercise and self-esteem: rationale and model. Med. Sci. Sports Exerc. Vol. 21, No. 3, pp. 329–337, 1989. Positive emotional and psychological benefits are commonly believed to result from chronic physical exercise. While reviews of research have failed to substantiate this general proposition, they have identified enhanced self-esteem as an empirically supported exercise outcome. Unfortunately, research in this area has tended to be simplistic in self-esteem theory and measurement and has remained incapable of addressing how or why change may occur. This paper summarizes pertinent self-esteem theory and presents an empirically based rationale for self-esteem enhancement through exercise participation. It constructs a model for examining exercise and self-esteem interactions in which components of self-structure are hierarchically organized on a basis of generality. The self-esteem model contains dimensions of competence and self-acceptance, and it is operationally defined.