A Safety and Efficacy Study of ABT-089 in Children With Attention-Deficit/Hyperactivity Disorder (ADHD)

* Have voluntarily signed an informed consent form * Meet diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD) based on detailed evaluation and interview with parent(s) * First grade or higher in a school setting 3 days/week * Subject is generally in good health based on medical history, physical examination, clinical lab tests, and ECG * Subject weighs at least 37 pounds (17 kg) * Female subjects of childbearing potential must have a negative urine pregnancy test at screening and baseline and agree to comply with applicable contraceptive requirements * Subject and parents have been judged by the study doctor to be reliable to keep required appointments for clinic visits and all tests, including blood draws, and examinations

* Subject is not functioning at an age-appropriate level intellectually * Subject has a current or past diagnosis of bipolar disorder, psychosis, autism, Asperger's syndrome, or pervasive developmental disorder * Current diagnosis of obsessive-compulsive disorder, eating disorder, anxiety disorder or depressive disorder requiring treatment of any kind * Subject has a history of significant allergic reaction to any drug * Subject requires ongoing treatment with any psychiatric medication * Subject has a serious medical condition, seizure disorder (except febrile seizures as an infant), or history of substance abuse or dependence