Acknowledging that the parent–child attachment is a dyadic relationship, we investigated differences between pairs of parents and preschool children based on gender configurations in the association between attachment and problem behavior. We looked at mother–daughter, mother–son, father–daughter, and father–son dyads, but also compared mothers and fathers, daughters and sons, and same versus different gender pairs. We employed multigroup structural equation modeling to explore moderation effects of gender in a sample of 446 independent pairs of parents and preschool children (2–5 years old) from the Netherlands. A stronger association between both secure and avoidant attachment and internalizing problems was found for father–son dyads compared to father–daughter dyads. A stronger association between both secure and avoidant attachment and externalizing problems was found for mother–son dyads compared to mother–daughter and father–daughter dyads. Sons showed a stronger negative association between secure attachment and externalizing problems, a stronger positive association between avoidant attachment and externalizing problems, and a stronger negative association between secure attachment and internalizing problems compared to daughters. These results provide evidence for gender moderation and demonstrate that a dyadic approach can reveal patterns of associations that would not be recognized if parent and child gender effects were assessed separately.