Starting in the 1960s, the U.S. Supreme Court understood the Establishment Clause to strictly limit government’s ability to promote religion in the schools: The state could not lead prayers, it could not fund private religious education, and it could not teach religion as true in the public school curriculum. During the same period, the Court construed free exercise rights (in schools and elsewhere) in a fairly modest fashion by balancing religious rights against government interests. Beginning in 1990, the Court weakened the Free Exercise Clause still further. Today, however, the Court is moving to reshape the general law of the Religion Clauses, and the trend points (clearly) toward a greatly weakened Establishment Clause and (less clearly) toward a Free Exercise Clause that is at least somewhat more robust. The Court has also made clear that the Free Speech Clause grants religious speakers equal rights to speak on school property. These speech protections are powerful guarantors of religious liberty, even if no revolution in free exercise law materializes. This chapter surveys the constitutional law involving religion in the K–12 public schools, summarizing that law as it currently stands and offering tentative predictions about where it is headed. The chapter begins with the Establishment Clause limits on government religious expression in the public schools, then continues by discussing the free exercise rights of students and teachers, religion in the public school curriculum, and the rights of religious groups to speak on school property.