Parents serve important functions in regulating children's responses to stress and challenge. However, the parental characteristics that modulate the effectiveness of parents as stress buffers remain to be fully characterized. To address this gap, this study examined parental characteristics and behaviors that may explain variation in parents’ ability to buffer cortisol responses to acute stress of 180 children (ages 9–11 years old, M = 9.9 years, SD = .58). Children were randomly assigned to either participate in a public speaking task, the Trier Social Stress Test – modified for children (TSST-M) or a control condition. Children in the TSST-M condition were randomly assigned to prepare for the public speaking task either with their parent (N = 59) or alone (N = 60), whereas 61 children were assigned to the control condition (no TSST-M). We found that parental education moderated the effect of condition on children's responses to acute stress. Children whose parents had lower levels of education exhibited reduced cortisol responses in the parent condition compared to the alone condition, showing a buffered pattern of reactivity. In contrast, children of parents with high levels of education displayed higher cortisol reactivity in the parent condition compared to the alone and control conditions. Parental education was also positively associated with higher levels of state anxiety within the parent condition. These results suggest that highly educated parents may emphasize performance over comfort, amplifying their children's state anxiety and cortisol responses to a public performance.