The short-term effects of public smoking bans on individual smoking and drinking habits were investigated in this paper. In 2005, a smoking ban was introduced in Italy, and we exploited this exogenous variation to measure the effect on both smoking participation and intensity and the indirect effect on alcohol consumption. Using data from the Everyday Life Aspects survey, for the period 2001-2007, we show that the introduction of smoke-free legislation in Italy significantly affected smoking behavior. We also document significant indirect effects on alcohol consumption for the main alcoholic beverage categories. A robustness analysis is also performed, to test the extent to which unobservable variables may bias our estimated parameters. Our results are then used to perform a cost-effectiveness analysis of the anti-smoking legislation in Italy.