This chapter focuses on the implications of both the descriptive and prescriptive aspects of gender stereotypes for women in the workplace. Using the Lack of Fit model, we review how performance expectations deriving from descriptive gender stereotypes (i.e., what women are like) can impede women's career progress. We then identify organizational conditions that may weaken the influence of these expectations. In addition, we discuss how prescriptive gender stereotypes (i.e., what women should be like) promote sex bias by creating norms that, when not followed, induce disapproval and social penalties for women. We then review recent research exploring the conditions under which women experience penalties for direct, or inferred, prescriptive norm violations.