The prevalence of substance use among emerging adults is substantial and increases risk for social, personal, and health consequences. Past research suggests considerable variation across gender and ethnic groups, but little of this research focuses on young Arab Americans. Participants were 179 emerging Arab American adults (68.7% male; mean age = 24) who identify as Muslim. Participants were recruited through Amazon Mechanical Turk (MTurk) to complete an online survey that focused on lifetime, past year, and past month tobacco, alcohol and marijuana use. Tobacco use was very common with over half of the men and a quarter of women reporting past year use. Despite religious and cultural prohibitions, rates of alcohol and marijuana use were also substantial. Men were more likely than women to report any use of each substance at each time point. And men, as compared to women, tended to report more frequent use of each substance at each time point. Higher levels of religiosity were related to lower levels of alcohol and marijuana use for both men and women. Religiosity was unrelated to tobacco use for males, but was related to less tobacco use for females. Religiosity did not significantly moderate the relationship between gender and any of the three types of substances, suggesting that gender and religiosity independently influence substance use rates. Implications for future research, education, and treatment are discussed.