Although single-sex education was once the norm in the U.S., the practice has largely been confined to private schools for more than a century. However, with the introduction of the final version of the U.S. Department of Education's so-called single-sex regulations in 2006, public schools were allowed greater flexibility to offer single-sex opportunities. As a result, the issue is receiving more attention from educators, policymakers, and parents. For a principal considering a single-sex program, careful planning and implementation will be important. Educators should also take care that implementation of single-sex classes or schools does not send a message that boys and girls "have innate limitations that have to be overcome." Finally, it is important to keep legal issues in mind. While the new Title IX regulations establish some parameters for single-sex education, there is obviously still room for interpretation--as well as legal challenges to both the new regulations or specific implementations of single-sex programs by public schools or districts. (Contains 4 online resources.)