This paper examines whether stereotype threat might reduce performance by imposing demands on the phonological component of the working memory system. If stereotype threat produces worries and concerns about the task at hand, then these worries might interfere with the part of working memory that is responsible for storing task-relevant verbal information. In Experiment 1, male and female math-identified participants completed easy and difficult tasks involving modular arithmetic under stereotype threat (with the study described as assessing "why men are generally better than women at math") or no stereotype threat (with the study assessing "why some people are better at math than are others"). Performance was poor only in the stereotype threat condition and only on problems that were difficult (i.e., horizontally-presented items that place high demands on working memory). In Experiment 2, participants completed math items that were high and low in the demands they place on working memory, and items were solved either as a single task or concurrently with a second task designed to reduce available phonological resources. Only completing demanding math problems reduced performance on the secondary task. Experiments 3A & 3B took advantage of this finding to assess the consequences of inducing stereotype threat. Highly-demanding math problems were less likely to be correctly answered under stereotype threat, and poor performance was accompanied by more self-reported task-related thoughts and worries. Experiment 4 showed that practice on demanding math items can attenuate stereotype threat effects, suggesting that practice reduces the demands of task performance on working memory capacity. Experiment 5 provided further evidence that stereotype threat affects the phonological component of working memory by demonstrating that performance on later unrelated verbal, but not on spatial, tasks were negatively affected following stereotype threat in math. These results show that stereotype threat undermines performance on tasks that are especially reliant on phonological resources and affects performance on subsequently encountered tasks that rely on those same resources. Moreover, practice and proceduralization can reduce the negative consequences of stereotype threat by reducing the need of phonological resources in problem solution.