In two studies, we demonstrate that small group discussions change the extent to which an activated stereotype affects performance in a relevant domain. In Study 1, female participants were asked why men are (or are not) better than them at maths. They generated their answers individually or through group discussion, and their subsequent maths performance was highest when they collectively challenged the stereotype and lowest when they collectively affirmed the stereotype. When participants affirmed the stereotype through discussion, they used more theories which supported the validity of the stereotype, compared to the individual thought condition; and consensus mediated the effect of group discussion on performance (relative to individual rumination). In Study 2, male and female participants affirmed or challenged the stereotype in same-gender discussion groups. After affirming the stereotype, women's performance decreased relative to their baseline scores and men's performance was ‘lifted’. In contrast, when they challenged the stereotype, there was no difference between the performance of men and women on the maths test. This pattern of effects was mediated by confidence in mathematical ability. The findings support the idea that topical small group discussions can, in the short term, differentially alter the impact that stereotypes have on performance.