This study examines the joint impact of parental origins and partner choice on the employment behavior of second-generation women in the United States. We find that endogamy (choosing a first- or second-generation partner from the same national-origin group) is associated with lower labor supply among second-generation women, net of the effects of parental origin culture as proxied using the epidemiological approach to cultural transmission. Parental origin effects are mediated by education, but endogamy curtails economic activity regardless of educational attainment. The findings are robust for married women. Findings for women in cohabiting unions are more heterogeneous, however: cohabitation appears to mute some of the relationship between parental origin culture and women’s economic behavior. In particular, the negative relationship between endogamy and women’s labor supply does not hold for women in cohabiting unions.