--- - |2 Binary gender and sexuality are socially constructed, but they structure thought at such a deep level that even those critical of sexism and homophobia can unwittingly reproduce them, with consequences felt most profoundly by those whose gender/sexual identity defy binary logic. This article outlines a generic pattern in the reproduction of inequality we call foreclosing fluidity, the symbolic or material removal of fluid possibilities from sexual and gender experience and categorization. Based on 115 responses from people who are both sexually and gender fluid and a reading of existing sociologies of gender and sexualities from a fluid standpoint, we demonstrate how lesbian/gay/straight, cisgender, and transgender women and men—regardless of intentions—may foreclose fluidity by mobilizing cisnormative, transnormative, heteronormative, and/or homonormative beliefs and practices. Examining patterns of foreclosing fluidity may provide insight into (1) the further incorporation of fluid people and standpoints into symbolic interactionism, and (2) the reproduction and persistence of sexual and gender inequalities. - 'Symbolic Interaction, EarlyView. '