The current study estimated trends in the prevalence of daily and nondaily cigarette smoking among United States adults with any common mental health or substance use problem (MHSUP), compared to US adults without MHSUP, from 2005 to 2014. Data were drawn from the years 2005 to 2014 from the public use data files for the annually conducted National Survey on Drug Use and Health. Linear time trends of current, daily, and nondaily cigarette smoking among adults (age 18 years and older) with and without MHSUP were assessed using logistic regression models with continuous year as the predictor. In 2014, the prevalence of current cigarette smoking among those with MHSUP was more than twice that of those without MHSUP. Nondaily cigarette smoking increased significantly from 2005 to 2014 among those with MHSUP (P = .001) in contrast to a decline in nondaily cigarette smoking among those without MHSUP (P < .01). The rate of change differed significantly (P < .001). Daily cigarette smoking declined significantly from 2005 to 2014 among those with and without MHSUP (P values < .001). The prevalence of nondaily cigarette smoking is increasing among US adults with common mental health and substance use problems, while it continues to decline among those without these vulnerabilities. The disparity in prevalence of daily cigarette smoking between those with and without MHSUP remains substantial. Conclusions about how to reach the tobacco endgame may need to be reconsidered to develop targeted tobacco control public health approaches that address common MHSUP.