Stereotype threat research shows that when stigmatized group membership is made salient, group members' cognitive performance is lowered; however, the mechanism through which this effect operates is not well understood. This study tests between arousal and ego depletion accounts of stereotype threat by examining whether stereotype threat effects are mitigated or exacerbated by increasing glucose levels. In a study of the effects of stereotype threat on women's mathematics performance, we find that glucose exacerbated stereotype threat effects, lending support to an arousal-based theory of stereotype threat. Findings also suggested the plausibility of an additional mechanism driving threat effects in which stigmatized individuals conserve scarce cognitive resources for use in subsequent, non-stigmatized domains. (Contains 3 endnotes and 5 figures.)