Background: More than half of US states have legalized medical marijuana. Several states have also legalized it for recreational use. In spite of states' actions, marijuana remains illegal under federal law. It remains to be seen, however, if the Trump administration will enforce federal law in states that have legalized marijuana. For now, it appears the move toward state legalization of marijuana will increase. Because of its legal status, research concerning the medical benefits of marijuana has been limited. Methods: We reviewed the literature pertaining to medical use and legalization of marijuana. Results: Available research shows that marijuana can benefit some conditions. There are also concerns about harmful effects on both individual and public health and whether legalization will lead to increased marijuana use among youth. Each of these elements has implications for school-based drug education programs. Researchers have shown that the 10 states with the highest rate of past month marijuana use by youth all have legalized recreational and/or medical use of marijuana, whereas none of the 10 states with the lowest rate of past month marijuana use by youth, has legalized marijuana. In the debate over legalization schools can potentially serve as a community resource, providing accurate information concerning marijuana. Conclusions: Teachers and parents should continue to discourage young people from using marijuana (as well as alcohol, tobacco, and other drugs).