Classified as a disruptive behavior, aggressive behavior stands out in the eyes of the parent and clinician. Aggressive behavior can be either impulsive (reacting to a trigger) or proactive (premeditated). Temper tantrums, physical aggression such as hitting or biting other children, stealing other children's possessions, and defiance of authority are distressing to families and school personnel. Often, it is in the school or child care setting that the behaviors become troublesome; the behaviors may interfere with family or peer relationships and school performance. Approximately 3% to 7% of children and adolescents manifest aggressive signs. During the course of normal development, families may experience periods when a child exhibits temper tantrums during toddler years or rebellion during adolescent years. These behaviors, when limited in time, are considered normal developmental occurrences. When they form a pattern over time, they are considered psychiatric disorders.