The objective of this study was to evaluate the efficacy of a multicomponent program for treating attention-deficit/hyperactivity disorder (ADHD) carried out by teachers in a classroom context. Dependent measures included neuropsychological tasks, behavioral rating scales for parents and teachers, direct observation of behavior in the classroom, and academic records of children with ADHD. Fifty children with ADHD participated in the study. The teachers of 29 of the 50 students were trained in the use of behavior modification techniques, cognitive behavior strategies, and instructional management strategies. The other 21 students formed the control group. Parents' and teachers'ratings detected improvements in primary symptoms (inattention-disorganization, hyperactivity-impulsivity) and in behavioral difficulties usually associated with ADHD (e.g., antisocial behavior, psychopathological disorders, anxiety). Furthermore, the results showed increased academic scores, enhanced classroom behavioral observations, and improved teachers' knowledge about the strategies directed toward responding to the children's educational needs.