Men and women occupy very different sectors of the labor market and women continue to be disadvantaged by this segregation in prestige, pay and power. Much research has examined how segregation is reproduced by discrimination and coercion, but as such actions become increasingly culturally illegitimate, we must begin to ask why gender inequality persists in the face of its illegitimacy. This project examines how two culturally-informed, individually -held sets of beliefs, gender schemas (beliefs about the appropriate roles and "essential natures" of men and women) and self-conceptions (gendered beliefs about the self) inspire decision-making that reproduces occupational gender segregation. Using 5-year longitudinal panel data of students from four institutions (MIT, Olin, Smith and UMass), I study how gender schemas and self-conceptions influence students' major selection and their career decisions 18 months after graduation. This project theorizes a phenomenon I call "the self-expressive edge of sex segregation," the reproduction of occupational sex segregation through the individualistic, self-reflective, yet culturally-informed decisions of social actors. This dissertation shows, first of all, that gender schemas and self-conceptions are indeed co-constructed: our most individualistic beliefs--who we think we are as people-- are informed by our adherence to cultural beliefs about gender. These culturally-informed self-conceptions not only help direct the distribution of men and women into already-segregated college majors and career fields, they help to reproduce the cultural sex-typing of such fields as "masculine" and "feminine" domains. As I show with a case study of engineering students, these individual-level beliefs can also interact with professional cultures in such a way that segregation is reproduced in the very process of learning to be a professional. In these mechanisms of sex segregation, cultural gender beliefs act through self-conceptions to influence career decisions. This cloaking of gendered career decision-making in individualistic self-expression may be particularly resistant to social change, as undermining individuals' self-expressive freedoms would be a culturally unacceptable method to reduce gender inequality