This paper compares the causes and consequences of employment instability among Mexican-origin women, White women, and White men. Data came from the work experience supplement in the March 1995 file of the Current Population Survey for a sample that included 1,399 Mexican-origin women, 17,092 White women, and 24,440 White men. All were experienced noninstitutionalized workers aged 16-64. In the unstable employment category were those workers who had experienced at least one episode of unemployment during the year or involuntary part-time work for the entire year. Using logistic regression, results show that Mexican-origin women with low levels of schooling, immigrants, those who were young, and those employed in the periphery services sector were highly vulnerable to employment instability. Although a high school diploma substantially reduced the risk of employment instability among Mexican-origin women, their employment instability was still greater than that of their White male and female counterparts. In terms of reducing employment instability, having some college education was more beneficial to Mexican-origin women than to Whites. Earnings determination models revealed that employment instability exerted a heavier penalty on the earnings of Mexican-origin women, compared to their White counterparts, net of human capital endowments and economic sector location. (Contains 28 references.) (SV)