We evaluate one of the most prevalent prohibitory policies: banning the sales of tobacco to teens. We exploit the staggered introduction of sales bans across Switzerland and the European Union from 1990 to 2016. The estimates indicate a less than 1 percentage point reduction in teen smoking because of the bans. The reduction is substantially lower than the 5 percentage point reduction expected by health officials. We examine additional outcomes relevant to assessing any prohibitory policy. We find that teens circumvent the bans through peers. Moreover, they consider smokers less cool but do not think smoking is more dangerous.