The present study examined Swedish mothers' and fathers' warmth towards their children in relation to their children's agency. It also examined the longitudinal relation between agency and children's externalising, internalising, and school achievement. Swedish children's mothers and fathers (N = 93) were interviewed at three time points (when children were 8, 9, and 10 years old) about their warmth towards their children, children's agency, and children's externalising and internalising behaviours and school achievement. Parental warmth at Time 1 was significantly correlated with child agency at Time 2, which was significantly correlated with child externalising and internalising behaviours and academic achievement at Time 3. There were no differences between girls and boys. Results from this study indicate that Swedish parents' warmth is directly related to subsequent perceptions of children's agency, which in turn are related to subsequently lower child externalising and internalising problems and higher academic achievement. These findings held in the context of a three-year longitudinal study and for both boys and girls, suggesting the importance of child agency in the link between parental warmth and children's adjustment.