It is normal for children and adolescents to occasionally argue with their parents and defy authority, particularly when they are tired, hungry, or upset. Boundary testing is also seen as a normal part of adolescent development; however, there are cases where challenges to adult authority goes beyond what is considered to be normal. When children and adolescents regularly express anger and aggression, they may meet the diagnostic criteria for oppositional defiant disorder. This overview of oppositional defiant disorder (ODD) in children and adolescents will discuss in detail the behaviors associated with oppositional defiant disorder and how youth receive this diagnosis. Also included in this overview are the factors that contribute to the development of oppositional defiant disorder as well as co-occurring disorders typically seen with ODD. Finally, this overview will discuss effective treatment approaches for oppositional defiant disorder in children and adolescents.