This article presents the first quantitative analysis of gender disparities in self-employment in urban China. It documents the extent of gender income inequality in self-employment. By disaggregating self-employment into three occupational classes, it reveals the gender segregation within self-employment – women were concentrated in the financially least rewarding segment – and identifies it as a main source of gender income inequality. I examine a range of determinants of participation in self-employment, including family structure, family background and career history, and how their gender-specific effects contribute to gender segregation. Although using data from a 1996 national survey, this study captures two key processes that shaped the structure of self-employment in contemporary urban China: the restructuring of the state sector and the growth of financial returns and social status in the private sector, both of which contributed to the formation of gender segregation in self-employment.