The purpose of this paper was to evaluate eight currently marketed sports bras for differences in control of vertical displacement of the breast, overall comfort scores, and overall support scores for A, B, C and D cup sizes. An additional goal was to determine and compare differences in the vertical displacement of the nude breast among the four cup size groups. To determine differences in vertical displacement, subjects were filmed while jogging on a treadmill, and film data were analyzed frame by frame. To determine differences in overall comfort and support ratings, subjects tested each of the eight bra styles under actual exercise conditions and subsequently completed an evaluation form. Significant differences in vertical displacement in the nude condition were found between the D cup size group and the other 3 cup sizes. Significant differences in the eight styles' abilities to control vertical displacement, and in overall comfort and support scores were found, both within the group as a whole and within each bra cup size group. Specific suggestions for further sports bra development and for individualized bra style selection are included.