We examine whether teams exert a positive influence on student test scores in three Team Based Learning (TBL) courses at two different universities. We find positive and significant effects on individual exam scores for students at all levels of the ability distribution; on average, an individual’s exam score increases roughly 6 points for every 10 point increase in their teammates’ average score. In addition, we find that these positive effects vary little across the ability distribution of teams and individuals, suggesting that the TBL method benefits a continuum of student abilities.