Background: Exposure to harsh parenting and children's skills in "Theory of Mind" (ToM) show independent and interacting associations with problem behaviors at age 2 (Hughes & Ensor, 2006). This study examined whether these age-2 measures also predict age-4 problem behaviors. Method: In a socially diverse sample (N = 120), multi-informant, multi-measure, multi-setting ratings indexed problem behaviors at ages 2, 3 and 4; children completed both ToM and verbal-ability tasks at age 2, while video-based ratings of maternal negative affect and control within dyadic mother-child play indexed harsh parenting. Results: Age-2 harsh parenting and ToM were independent and interacting predictors of age-4 problem behaviors, even with age-2 problem behaviors, verbal ability and social disadvantage all controlled. The interaction between harsh parenting and ToM distinguished persistent vs. diminishing problem behaviors. Conclusions: Both child and family characteristics predict increases in problem behaviors from 2 to 4; adverse effects of harsh parenting are attenuated for children with good ToM skills.