This study investigates the degree to which subgroup (Black-White) mean differences on various assessment center exercises (e.g., in-basket, role play) may be a function of the type of exercise employed; and furthermore, begins to explore why these different types of exercises result in subgroup differences. The sample consisted of 633 participants who completed a managerial assessment center that evaluated them on 14 ability dimensions across 7 different types of assessment exercises. In addition, each participant completed a cognitive ability measure. The results suggest that subgroup differences varied by type of assessment exercise; and furthermore that the subgroup difference appeared to be a function of the cognitive component of the exercise. Lastly, preliminary support is found that the validity of some of the assessment center exercises in predicting supervisor ratings of job performance is based, in part, on their cognitive component; however, evidence of incremental validity does exist.