From zero to a hundred in a split second: understanding aggression in an eight-year-old child.

Xavier is an eight-year-old American boy of Italian ancestry in a second-grade inclusion classroom at a public elementary school. He carries diagnoses of a severe language-based learning disorder (LD) and attention-deficit/hyperactivity disorder (ADHD). He lives with his mother, twin sister, and older teenage brother; his parents are in the process of divorcing. The Office of Special Education referred Xavier to a child psychiatrist (NR) for evaluation due to its increasing concerns about both his academic progress and his level of impulsivity and aggressive behavior (biting, head butting, kicking, throwing chairs, and running unsupervised down the street outside the school). Although many of these behaviors are not new, this referral was prompted by increasing concerns about safety. The evaluation included record reviews, interviews with parents and school personnel, and a classroom observation of Xavier. Several examples will illustrate the behavioral challenges that Xavier presents. During recess, Xavier was trying to explain to a teacher that his ball had gone over the