According to the Mahanoy Area School District, it can punish any off-campus speech that “disrupts the school.” And “disruption,” the school district adds, occurs whenever off-campus speech “‘upset[s]’” other students. This approach to the First Amendment has little basis in our history and tradition. If the Court adopts it, especially in these hypersensitive times, the results will be predictable: Students who reject the prevailing campus orthodoxy will self-censor their speech at home. Not because they should. Not because their parents disapprove. But because they fear the backlash at school. And while public schools placate the mob, parents’ authority to raise, teach, and discipline their children will suffer.