OBJECTIVE To evaluate the predictors of persistence and the timing of remission of attention-deficit hyperactivity disorder (ADHD). METHODS Subjects were 6- to 17-year old Caucasian, non-Hispanic boys with and without ADHD. DSM-III-R structured diagnostic interviews and blind raters were used to examine psychiatric diagnoses, cognitive achievement, social, school, and family functioning at a 4-year follow-up assessment. RESULTS At the 4-year follow-up assessment, 85% of children with ADHD continued to have the disorder and 15% remitted. Of those who remitted, half did so in childhood and the other half in adolescence. Predictors of persistence were familiality of ADHD, psychosocial adversity, and comorbidity with conduct, mood, and anxiety disorders. CONCLUSIONS The findings prospectively confirm that the majority of children with ADHD will continue to express the disorder 4 years later. For a minority of children, ADHD was a transient disorder that remits early in development. In addition, we have shown that persistence of ADHD is predictable. Familiality, adversity, and psychiatric comorbidity may be clinically useful predictors of which children with ADHD are at risk for a persistent disorder.