SUMMARYA controlled investigation was conducted to assess the relative effectiveness of amitriptyline and methylphenidate for treating hyperactive/aggressive behavior in children originally referred to a learning clinic. Behavioral change was measured through parent and teacher ratings. Drug effects on attention, short term memory, and impulsivity were evaluated with laboratory tasks. It was found that both drugs were largely comparable in attenuating hyperactivity and aggression. Of the laboratory measures, only attention was improved by both drugs. However, neither medication interfered with functioning on the other laboratory tests. With the exception of and trip by line‐induced sedation, side effects were of minor degree. Findings raised questions concerning measuring and improving attentiveness. Differences between results of this and other studies were discussed, as were issues regarding pharmacotherapy with amitriptyline in childre