While at least a dozen state legislatures are considering bills to allow the consumption of marijuana for medicinal purposes, the federal government has recently intensified its efforts to close medical marijuana dispensaries. Federal officials contend that the legalization of medical marijuana encourages teenagers to use marijuana and have targeted dispensaries operating within 1,000 feet of schools, parks and playgrounds. Using data from the national and state Youth Risk Behavior Surveys, the National Longitudinal Survey of Youth 1997 and the Treatment Episode Data Set, we estimate the relationship between medical marijuana laws and marijuana use. Our results are not consistent with the hypothesis that legalization leads to increased use of marijuana by teenagers.