The National Health Interview Survey (NHIS) first began collecting data about e-cigarette use in 2014. The estimates presented in this report provide a foundation for understanding who is using e-cigarettes and for monitoring changes in e-cigarette use among U.S. adults over time. In 2014, men were more likely than women to have ever tried e-cigarettes but were not more likely to be current users. Younger adults were more likely than older adults to have tried e-cigarettes and to currently use e-cigarettes. Both non-Hispanic AIAN and non-Hispanic white adults were more likely than non-Hispanic black, non-Hispanic Asian, and Hispanic adults to have ever tried e-cigarettes and to be current e-cigarette users. When examined in the context of conventional cigarette smoking, use of e-cigarettes was highest among current and recent former cigarette smokers, and among current smokers who had made a quit attempt in the past year. Although fewer than 4% of adults who had never smoked conventional cigarettes had ever tried an e-cigarette, nearly 1 in 10 never-smokers aged 18–24 had tried an e-cigarette at least once.