Choi NG, et al. - Using data from the 2015–2017 National Survey on Drug Use and Health (N = 26,322 aged 50+), researchers sought to determine: (1) associates of use-to-nonuse (use 13-24 months ago, but no past-year use), initiation/reinitiation (no use 13–24 months ago, but past-year use), and continued use over a 24-month period; and (2) relationships of past-year marijuana use disorder with use/nonuse among older adults. Among participants aged 50–64 years, 2.1% were users-to-nonusers, 2.2% initiators/reinitiators, and 7.2% continued users and among participants aged 65+ years age, the corresponding percentages were 0.7%, 0.7%, and 2.4%. Users-to-nonusers vs continued users were less frequent in correlation with residence in states with medical marijuana laws, nicotine dependence, and other illicit drug use. A higher likelihood of initiation/reinitiation was observed in correlation with alcohol use disorder. They observed the correlation of parole/probation status with a higher likelihood of use-to-nonuse. A higher likelihood of both use-to-nonuse and initiation/reinitiation was observed in correlation with moderate/great marijuana risk perceptions. Continued users vs initiators/reinitiators or medical vs recreational users did not differ in the odds of marijuana use disorder. Findings support the necessity for treatment in substantial numbers that had marijuana and other substance use problems.