Results. The age-adjusted smoking prevalence of adults with mental illness or serious psychological distress ranged from 34.3% (phobias or fears) to 59.1% (schizophrenia) compared with 18.3% of adults with no such illness. Smoking prevalence increased with the number of comorbid mental illnesses. Cessation attempts among persons with diagnosed mental illness or serious psychological distress were comparable to attempts among adults without mental illnesses or distress; however, lower quit ratios were observed among adults with these diagnoses, indicating lower success in quitting.