The aims of this study were to examine mother-teacher agreement on oppositional defiant disorder (ODD) and conduct disorder (CD) symptoms and diagnoses in preschool children; to determine if context is a source of disagreement; and to explore if sex, referral status, and age moderated agreement rates. Participants included 158 male and 139 female 3- to 5-year old preschool children, their mothers, and teachers. A structured interview, the Kiddie-Disruptive Behavior Disorder Schedule was used for maternal report and teachers completed the Early Childhood Inventory. Results indicated that mothers reported more symptoms and diagnoses of ODD and CD than teachers, and mother-teacher agreement on both ODD and CD symptoms and diagnoses was low. Level of mother-teacher agreement increased when reporting on behavior in the same context; however, the rates remain modest. Referral status increased the likelihood of mother and teacher agreement on several ODD and CD symptoms, as well as ODD and CD diagnosis. These data suggest that context plays a role in mother-teacher agreement in the assessment of young children's ODD and CD symptoms.