Negative perceptions about the child and child behavior are implicit in parenting stress, a construct associated with suboptimal parenting and child outcomes. We examined the extent to which individual differences in mothers' mental representations of their children (mind-mindedness) were related to parenting stress and observed parenting behavior. Participants were 86 Australian mothers and their 4-year-olds who were enrolled in a prospective study. Mind-mindedness was coded from mothers' descriptions of their child, mothers completed a self-report measure of parenting stress, and maternal behavior during free-play was videotaped and coded using the Emotional Availability (EA) Scales, Version 3. Mothers who used more mental state words when describing their child reported lower parenting stress and showed less hostility when interacting with their children. Mothers who used more positive mental state descriptors were rated as more sensitive during interaction. The relation between mind-mindedness and negative maternal behavior was indirect, and mediated through parenting stress. Clinical implications of the findings for families and childcare settings are discussed.