The Multimodal Treatment of Attention Deficit Hyperactivity Disorder (MTA) Study was conducted at the following research sites in the United States and Canada:

• New York State Psychiatric Institute at Columbia University, New York, NY
• Mount Sinai Medical Center, New York, NY
• Duke University Medical Center, Durham, NC
• University of Pittsburgh, Pittsburgh, PA
• Long Island Jewish Medical Center, New Hyde Park, NY
• Montreal Children's Hospital, Montreal, Canada
• University of California, Berkeley, CA
• University of California, Irvine, CA