Lifetime nonmedical use of the following prescription drugs was assessed for the purposes of the current study: pain relievers (eg, opioid analgesics), tranquilizers (eg, benzodiazepines and muscle relaxers), sedatives (eg, barbiturates, Quaaludes), and stimulants (eg, methylphenidate). A composite variable was created by the Substance Abuse and Mental Health Services Administration that encapsulated use of any of these broad drug classes. To determine nonmedical use of prescription pain relievers, for example, participants were asked, “Have you ever, even once, used any type of prescription pain reliever that was not prescribed for you or that you took only for the experience or feeling it caused?” Lifetime use of illicit drugs examined in the current analysis included marijuana, cocaine, crack cocaine, heroin, hallucinogens, inhalants, and methamphetamine. A composite variable was also created that encapsulated any illicit substance use. To determine illicit drug use such as heroin in the NSDUH, respondents were asked, “These next questions are about heroin. Have you ever, even once, used heroin?” This question was repeated for all of the aforementioned illicit drugs.