<p>Parenting stress has become an increasingly critical issue in adult development. In this context, the present study investigated the association between ambivalent sexism and parenting stress, as well as the mediating role of the parent-grandparent coparenting relationship. A questionnaire containing validated scales measuring ambivalent sexism, parent-grandparent coparenting relationship, and parenting stress, was administered to 236 pairs of dual-earner couples. Data were analyzed using the actor-partner interdependence mediation model. The results indicated that husbands scored significantly higher than wives on hostile sexism, while no gender differences were found in benevolent sexism, coparenting relationship, or parenting stress. The actor-partner interdependence mediation model demonstrated good model fit and revealed significant actor effects for both spouses, whereas partner effects were only for husbands. The parent-grandparent coparenting relationship served as a significant mediator in these associations. The current study contributes to theoretical studies on ambivalent sexism and parenting stress while also offering important practical implications for encouraging fertility and reducing parenting stress.</p>