The current study examines inconsistent discipline as a mediator in the association between maternal distress and child aggression and attention problems. Participants were 215 boys, ranging in age from 9 to 12 years, and their mothers. Mothers provided self-report data on socioeconomic status (SES), parenting stress, maternal distress (depression and anxiety/somatization), and use of parenting practices. They also rated their sons' levels of aggression and attention problems. Of five parenting practices measured, inconsistent discipline was most clearly related to the maternal and child variables of interest. Regression analyses indicated that inconsistent discipline partially mediated the relation between maternal distress and child aggression, when controlling for SES and stress, whereas the mediating role of inconsistent discipline in the association between maternal distress and attention problems was not supported. The different pattern for attention problems, which also includes nondisruptive behaviors, suggests that this mediation may be specific to certain types of child behavior. Given that aggressive behaviors in childhood often lead to more serious delinquency in adolescence, these findings are important for informing prevention and intervention efforts. The need for future research to examine other mediators also is discussed. (Contains 5 tables and 1 figure.)