This paper uses a regression discontinuity design to estimate the impact of the minimum legal tobacco purchase age (MLTPA) laws on smoking behavior among young adults. Using data from the confidential version of National Longitudinal Survey of Youth (1997 Cohort), which contains information on the exact birth date of the respondents, we find that the impact of the MLTPA on several indicators of smoking among youth is moderate but often statistically insignificant. However, for those who reported to have smoked before, we show that granting legal access to cigarettes and tobacco products at the MLTPA leads to an increase in several indicators of smoking participation, including up to a 5 percentage point increase in the probability of smoking. These results imply that policies that are designed to restrict youth access to tobacco may only be effective in reducing smoking behavior among certain groups of young adults. (JEL I10, I18, I19)