The study examined the reinforcing effects of ad libitum smoking with and without ADHD medication in adult smokers with clinically diagnosed ADHD. Participants were adults with ADHD. The effects of two day of ADHD medication compared to two days on placebo for were studied on nicotine intake (i.e., cotinine levels). In addition, task performance on the Continuous Performance Task and nicotine withdrawal symptoms were examined in response to ADHD medication + smoking a cigarette versus ADHD medication + abstinence versus placebo medication + smoking versus placebo medication + abstinence.