AbstractIt is well known that parenthood can be particularly stressful. However, less is known about the stability of parenting stress across children's developmental periods. Certain correlates to parenting stress, such as coparenting support between parents, also appear to play a crucial role in childrearing. The current study aims to shed light on the longitudinal associations between parenting stress during the preschool and school years, along with the moderating effect of coparenting support in this association. Eighty‐two heterosexual couples who are parents completed the Parenting Stress Index at Time 1 and Time 2 and the Coparenting Relationship Scale at Time 2. Actor‐Partner path analyses revealed that greater parenting stress in each parent was related to their partner's greater parenting stress at each time point, but only to their own greater parenting stress 5 years later. The association between fathers' parenting stress at both time points was weaker in fathers who reported greater coparenting support from their partner. Helping parents reduce their parenting stress and learn to support each other effectively as coparents may be important parenting intervention avenues.