use disorders from 61.4% to 42.6%, for an average annual percentage change of −2.6 (95% CI, −3.1 to −2.0) and among those without drug use disorders from 26.0% to 17.7%, for an average annual percentage change of −3.0 (95% CI, −3.2 to −2.7), as shown in eTable 1. 1 Notably, the difference in past-month prevalence of cigarette smoking between individuals with and without drug use disorders declined in the US from 35.5% in 2006 to 25.0% in 2019. 1 Moreover, our study 1 found that in the US from 2006 to 2019, past-month prevalence of cigarette smoking significantly declined among those with past-year MDE from 37.3% to 24.2%, among those with past-year SUD from 46.5% to 35.8%, and among those with past-year MDE and SUD from 50.7% to 37.0%. From 2006 to 2019, the difference in past-month prevalence of cigarette smoking between individuals with and without MDE declined significantly from 11.5% to 6.6%. 1 Prior studies [2][3][4] have not demonstrated declines in pastmonth prevalence of cigarette smoking in individuals with SUD and other mental illnesses, highlighting the novelty of our findings. 1 Furthermore, among adults with MDE and/or SUD, our results showed that the lifetime prevalence of cigarette smoking did not decline as much as past-month prevalence, indicating that the reductions in past-month smoking were due to quitting at some time after onset of smoking. Thus, tobacco cessation explains the relative improvements in pastmonth prevalence of cigarette smoking. 1 Our study 1 demonstrates that progress has been made by public health tobacco control measures and prevention intervention efforts for adults in the US, including those with MDE or SUD. However, higher past-month prevalence of smoking persists among adults with MDE or SUD, highlighting the ongoing need for smoking cessation efforts that target these individuals. We hope that our study will stimulate future work to better address cigarette smoking among people with SUD and other mental illnesses.