There are concerns over nonmedical use of prescription stimulants among youths, but little is known about the extent of use among young Asian-Americans, Native Hawaiians/Pacific Islanders (NHs/PIs), and mixed-race individuals-the fastest growing segments of the U.S. population. We examined prevalences and correlates of nonmedical stimulant use (NMSU) and disorder (StiUD) for these underrecognized groups. Whites were included as a comparison. Data were from young individuals aged 12-34 years in the 2005-2012 National Surveys on Drug Use and Health. We used logistic regression to estimate odds of past-year NMSU status. Significant yearly increases in lifetime NMSU prevalence were noted in Whites only. NHs/PIs (lifetime 7.33%, past-year 2.72%) and mixed-race individuals (10.20%, 2.82%) did not differ from Whites in NMSU prevalence (11.68%, 3.15%). Asian-Americans (lifetime 3.83%, past-year 0.90%) had lower prevalences than Whites. In each racial/ethnic group, "Methamphetamine/Desoxyn/Methedrine or Ritalin" was more commonly used than other stimulant groups; "got them from a friend/relative for free" and "bought them from a friends/relative" were among the most common sources. Females had greater odds than males of NMSU (among White, NH/PI, mixed-race individuals) and StiUD (among mixed-race individuals). Young adults (aged 18-25) had elevated odds of NMSU (White, NH/PI); adolescents had elevated odds of StiUD (White, mixed-race). Other substance use (especially marijuana, other prescription drugs) increased odds of NMSU and StiUD. NHs/PIs and mixed-race individuals were as likely as Whites to misuse stimulants. Research is needed to delineate health consequences of NMSU and inform prevention efforts for these understudied, rapidly-growing populations.