Abstract Introduction Young adulthood is a critical period for the adoption of risk behaviors like tobacco use. Protective factors in adolescence may promote a tobacco-free transition to young adulthood. We examine associations between the frequency of parental anti-smoking encouragement in adolescence and cigarette and e-cigarette use in young adulthood. Aims and Methods We analyzed data from Waves 1 (2009–2010, 10th grade, mean age = 16.2 years) and 5 (2013–2014 mean age = 20.3 years) of the US nationally representative NEXT Generation Health Study (n = 1718). At Wave 1, participants reported how often their parents or guardians encourage them to not smoke cigarettes (1 = Rarely or Never, 7 = Frequently). We used separate weighted multiple logistic regression models to model Wave 5 past 30-day cigarette and e-cigarette use as functions of the frequency of parental anti-smoking encouragement at Wave 1, adjusting for sociodemographic and parenting factors, initial substance use, and peer tobacco use. Results The average frequency of parental encouragement to not smoke cigarettes was fairly high (mean = 5.35). At Wave 5, 24.7% and 14.2% of respondents reported cigarette and e-cigarette use in the past 30 days, respectively. Greater frequency of parental anti-smoking encouragement was associated with lower odds of subsequent cigarette smoking (adjusted odds ratio 0.91, 95% confidence interval 0.83, 0.99) but its association with e-cigarette use was not significant (adjusted odds ratio 0.93, 95% confidence interval 0.84, 1.04). Conclusions The longitudinal negative association between anti-smoking encouragement and cigarette use suggests that parental anti-tobacco communication could be a long-term protective factor against young adult tobacco use. Our findings may also suggest the importance of product-specific messages in the evolving tobacco use landscape. Implications This study builds upon prior investigations of parenting in adolescence as a protective factor against young adult risk behavior. We isolate the frequency of anti-smoking encouragement during adolescence as an actionable factor distinct from other parenting variables. Our findings also suggest that message specificity may be an important factor in parental anti-tobacco communication as youth and young adult tobacco use becomes increasingly dominated by e-cigarettes.