The passage of the Family Smoking Prevention and Tobacco Control Act in 2009 provided the FDA with regulatory authority to reduce the nicotine content of cigarettes to levels that would decrease the addictive potential of cigarettes. Although such a regulatory strategy would likely have a significant positive impact on public health, such policy may have unintended consequences for certain vulnerable populations, including those with psychiatric comorbidity. Individuals with Attention Deficit Hyperactivity Disorder (ADHD) are more likely to smoke cigarettes than the general population, start smoking at a younger age, progress to regular use and dependence more quickly, smoke more and are more dependent, experience more severe withdrawal symptoms during acute abstinence, and have a harder time quitting. Given their increased risk across a range of smoking outcomes, smokers with ADHD may exhibit clinical deterioration or consume other tobacco products if the nicotine content of cigarettes were substantially altered. The overall goal of the proposed project is to examine the effects of very low nicotine content (VLNC) cigarettes on smoking behavior and clinical functioning in young adult smokers with ADHD. We will capitalize on existing expertise, infrastructure, and collaborative projects in this 2-site trial to recruit a large cohort of regula smokers with ADHD. Following careful characterization of baseline smoking, participants will be randomized (1:1) to smoke either regular nicotine content (0.8 mg/cig) cigarettes or VLNC cigarettes (0.05 mg/cig) for a period of 6 weeks and we will measure a range of smoking and ADHD-related outcomes.