The importance of parent engagement in children’s schooling is well documented, yet there is limited research on the quality of parent–teacher relationships specifically. In the present study, we aimed to help build knowledge in this area by investigating parent and teacher reports of home–school cooperation during children’s first year of school in Norway. Associations between parents’ and teachers’ reports of cooperation were examined as predictors of children’s academic skills and social functioning during their first year of school in Norway (N = 932). Controlling for children’s achievement and behavior prior to school entry, children whose parents and teachers both reported very good cooperation with one another were rated as having better academic skills and social skills and as having fewer negative behaviors than children whose parents and teachers did not report very good cooperation. In addition, if both parents and teachers reported very good cooperation, children’s academic skills were rated as higher than if parents and teachers disagreed such that one reported very good cooperation, but the other did not.