This report presents data from the 2015 National Survey on Drug Use and Health (NSDUH) for substance use treatment, and data from the 2002 through 2015 NSDUHs for mental health service use among adults aged 18 or older. Estimates for the receipt of substance use treatment (i.e., treatment for problems related to the use of alcohol or illicit drugs) are presented for young adults aged 18 to 25 and for adults aged 26 or older. Estimates for mental health service use are shown for young adults, adults aged 26 to 49, and those aged 50 or older. Where trends for mental health service use are presented, the report focuses on long-term trends by comparing estimates from the 2015 NSDUH with comparable estimates from 2002 to 2014 (or from 2008 to 2014 for selected estimates). Statistically significant differences are noted between estimates in 2015 and those in prior years. Trends for substance use treatment and other related estimates are not reported because of methodological changes in 2015.