Objectives. We assessed the characteristics associated with the awareness, perceptions, and use of electronic nicotine delivery systems (e-cigarettes) among young adults. Methods. We collected data in 2010-2011 from a cohort of 2624 US Midwestern adults aged 20 to 28 years. We assessed awareness and use of e-cigarettes, perceptions of them as a smoking cessation aid, and beliefs about their harmfulness and addictiveness relative to cigarettes and estimated their associations with demographic characteristics, smoking status, and peer smoking. Results. Overall, 69.9% of respondents were aware of e-cigarettes, 7.0% had ever used e-cigarettes, and 1.2% had used e-cigarettes in the past 30 days. Men, current and former smokers, and participants who had at least 1 close friend who smoked were more likely to be aware of and to have used e-cigarettes. Among those who were aware of e-cigarettes, 44.5% agreed e-cigarettes can help people quit smoking, 52.8% agreed e-cigarettes are less harmful than cigarettes, and 26.3% agreed e-cigarettes are less addictive than cigarettes. Conclusions. Health communication interventions to provide correct information about e-cigarettes and regulation of e-cigarette marketing may be effective in reducing young adults' experimentation with e-cigarettes.