INTRODUCTION: Major knowledge gaps regarding medical and nonmedical prescription stimulant use and illegal stimulant use (i.e., cocaine/crack/methamphetamine) by sexual identity and gender have implications for individuals' health and well-being. This study improves stimulant use measurement by differentiating the type of stimulant use and focusing on lesbian, gay, and bisexual subpopulations. METHODS: Data were pooled for adults in the 2015-2017 National Survey on Drug Use and Health (n=126,463; analyzed in 2019). Gender-stratified logistic regression models examined associations between sexual identity and past-year illegal stimulant use. Gender-stratified multinomial logistic regression models estimated odds of (1) medical use only versus no past-year prescription stimulant use, (2) any nonmedical stimulant use versus no past-year use, and (3) any nonmedical stimulant use versus medical use only. RESULTS: Illegal stimulant use varied by sexual identity (men: gay, 9.2%; bisexual, 7.5%; heterosexual, 3.2%; women: gay/lesbian, 3.2%; bisexual, 7.8%; heterosexual, 1.5%), as did nonmedical prescription stimulant use. Relative to same-gender heterosexuals, gay (AOR=2.61, 95% CI=2.00, 3.40) and bisexual (AOR=1.70, 95% CI=1.24, 2.33) men had higher odds of past-year illegal stimulant use, as did gay/lesbian (AOR=1.63, 95% CI=1.16, 2.28) and bisexual (AOR=2.70, 95% CI=2.23, 3.26) women. Sexual minorities reported higher odds of nonmedical prescription stimulant use than heterosexuals. Any nonmedical prescription opioid use was reported by 26.4% of people who reported nonmedical stimulant use and 27.0% of people who reported illegal stimulant use. CONCLUSIONS: Lesbian, gay, and bisexual individuals had a higher prevalence of stimulant use than their heterosexual counterparts. This has important implications for health disparities, especially given the high levels of polysubstance use. Taking a multilevel approach is crucial to reduce stimulant-related harms for lesbian, gay, and bisexual individuals.