This study presents the first nationally-representative estimates of adolescent nicotine prevalence that take into account adolescent reports of substances vaped. These reports allow nicotine estimates that consider the impact of the newly-emerged group of adolescents who report vaping only non-nicotine substances such as flavoring and/or marijuana and do not use nicotine in any form - a group typically treated as nicotine users.Data come from Monitoring the Future and are a randomly-selected subsample of 2231 U.S. 12th grade students who answered surveys with detailed questions on tobacco use and vaping in 2017.Among 12th grade students 24.7% used nicotine in the last 30 days. This estimate does not include the 3.8% of students who vaped only non-nicotine substances and did not use nicotine in any other form. These students more closely resemble their peers who do not use nicotine than those who do, in terms of perceived risk and disapproval of cigarettes, as well as percentage of friends who use cigarettes.A decline in nicotine prevalence was statistically significant, but not strikingly large, after taking into account students who vape non-nicotine substances and do not use nicotine in any form. These students are largely similar to their peers who do not use nicotine, which underscores the importance of efforts to alert youth that they may be vaping nicotine unknowingly, and prevent them from doing so.