Our thesis is that the degree of permissible interaction between government and religion and its policy implications is most strikingly documented in the educational arena. To support our claim, we make three arguments: (1) by the early 1970s, New York, Pennsylvania, Rhode Island, and other states were experimenting with accommodationist policies in education that neither increased religious divisiveness nor denied religious freedom. These policy experiments contributed to the Supreme Court’s new understanding of religious accommodation under the First Amendment; (2) beginning in the late 1970s, a scholarly reappraisal of the establishment clause—based on a close reading of the debates over the First Amendment in Congress and the states—was demonstrating that reasonable governmental accommodations, particularly in education, would not violate the establishment clause; and (3) that periodizing the establishment clause’s history, by focusing on state-level innovations and scholarly reinterpretations, enhances the understanding of the policy developments of the First Amendment, particularly in the educational field.