The objective of this study is to evaluate the long-term safety and tolerability of ABT-089 in adults with ADHD.

Inclusion Criteria:

• The subject was randomized into Study M06-855 and completed treatment in Periods 1 and 2 and the 2-week Extension Period
• If female, subject must be either postmenopausal for at least 1 year, surgically sterile (bilateral tubal ligation, bilateral oophorectomy or hysterectomy), or practicing at least a method of birth control throughout the study
• If female, the result of a pregnancy tests are negative
• The subject is judged to be in generally good health

Exclusion Criteria:

• More than 7 days have elapsed since the last dose of study drug in Study M06-855
• The subject has taken any ADHD medication between the last dose of study drug in Study M06-855 and the first dose of study drug in the current study
• The subject anticipates a move outside the geographic area