Three studies tested the hypothesis that negative metacognitive interpretations of anxious arousal under stereotype threat create cognitive deficits in intellectually threatening environments. Study 1 showed that among minority and White undergraduates, anxiety about an intelligence test predicted lower working memory when participants were primed with doubt as compared to confidence. Study 2 replicated this pattern with women and showed it to be unique to intellectually threatening environments. Study 3 used emotional reappraisal as an individual difference measure of the tendency to metacognitively reinterpret negative emotions and found that when sympathetic activation was high (indexed by salivary alpha-amylase), women who tended to reappraise negative feelings performed better in math and felt less self-doubt than those low in reappraisal. Overall, findings highlight how metacognitive interpretations of affect can undermine cognitive efficiency under stereotype threat and offer implications for the situational and individual difference variables that buffer people from these effects.