More than a trait of individuals, gender is an institutionalized system of social practices. The gender system is deeply entwined with social hierarchy and leadership because gender stereotypes contain status beliefs that associate greater status worthiness and competence with men than women. This review uses expectation states theory to describe how gender status beliefs create a network of constraining expectations and interpersonal reactions that is a major cause of the “glass ceiling.” In mixed-sex or gender-relevant contexts, gender status beliefs shape men's and women's assertiveness, the attention and evaluation their performances receive, ability attributed to them on the basis of performance, the influence they achieve, and the likelihood that they emerge as leaders. Gender status beliefs also create legitimacy reactions that penalize assertive women leaders for violating the expected status order and reduce their ability to gain complaince with directives.