This study examines the relation between parent and teacher ratings of oppositional behaviors in children from kindergarten to second grade. One cross-sectional sample of 85 boys in kindergarten, first, and second grade was assessed for problem behavior by reports from the children, parents, teachers, and trained observers. The second sample consisted of parent and teacher ratings of both boys and girls in a longitudinal design at 5 and 7 years of age. Results from both studies indicate that agreement does increase around the time of the child’s transition into school, and that each informant influences the ratings of the others over time.