Smokers with co-occurring mental illness or substance use disorders are not designated a disparity group or priority population by most national public health and tobacco control groups. These smokers fulfill the criteria commonly used to identify groups that merit special attention: targeted marketing by the tobacco industry, high smoking prevalence rates, heavy economic and health burdens from tobacco, limited access to treatment, and longer durations of smoking with less cessation. A national effort to increase surveillance, research, and treatment is needed. Designating smokers with behavioral health comorbidity a priority group will bring much-needed attention and resources. The disparity in smoking rates among persons with behavioral health issues relative to the general population will worsen over time if their needs remain unaddressed.