Pandemic influenza response plans have placed a significant emphasis on school closures as a community mitigation strategy. However, school closures raise serious ethical concerns, many of which have been largely overlooked. First, evidence of this intervention's efficacy has not yet been firmly established, calling into question whether it will be useful against the threat. Second, school closures have the potential to create serious adverse consequences, which will disproportionately affect vulnerable populations. Thus, policy makers should focus on gathering more evidence about the efficacy of school closures and on strengthening communication and transparency about the strengths and weaknesses of any school-closure plan that they decide to adopt. Policy makers should also consider intermediate options, such as partial school closures, which might provide ways to reap many of the benefits of school closings, while minimizing the costs. Finally, policy makers must labor to ensure that the benefits and the burdens of any interventions are distributed equitably.