Little is known about the causes of maternal parenting stress in the Mexican American population. We examine determinants of parenting stress among Mexican American mothers in comparison to non-Hispanic white and non-Hispanic black mothers. We base our analysis on Belsky's conceptual model (1984), which specifies predictors of parenting stress in three domains: maternal characteristics, child characteristics, and social context. Using data from the Fragile Families and Child Wellbeing Study, a national survey of new mothers conducted in large cities beginning in 1998, we draw a sample of 2,898 mothers from diverse racial and ethnic backgrounds. Our findings suggest differences in the determinants of parenting stress by racial or ethnic group. Overall, the patterns of parenting stress for non-Hispanic white and non-Hispanic black mothers are fairly consistent with Belsky's parenting model. However, for Mexican American mothers social support, but not partner support, ameliorate parenting stress and depression is not associated with parenting stress. Importantly as well, despite significant social disadvantage, the levels of parenting stress in Mexican American mothers does not significantly differ from those of non-Hispanic whites. Specific recommendations are made to practitioners for culturally competent responses to parenting stress in the provision of social services to Mexican American families. Implications for future research are twofold: our study calls for the incorporation of diverse samples when examining the determinants of parenting stress and for the development of theoretical frameworks that reflect the unique aspects of psychosocial well-being among Mexican Americans.