This case, which deals with the issue of prayer and related practices in public schools, is essentially a rerun of Engel v. Vitale from 1962. In its decision in Schempp, the Court basically said "we meant what we said" in the previous year's case.

The reaction to Engel, wherein the Court struck down the use of a school-scripted general prayer declaring obedience to God, had been hostile. The Court had been accused of "legislating -- they never adjudicate -- with one eye on the Kremlin and the other on the NAACP", and one Congressman called it "the most tragic [ruling] in the history of the United States." A Gallup Poll indicated that 76% of American citizens supported the concept of a Constitutional Amendment to reverse the effects of Engel and, later, Schempp. None made it through Congress.

The present case was brought by the Schempp family, supported by the ACLU which was prosecuting the case, objecting to a Pennsylvania law requiring that ten verses of the Bible be read at the start of every public school day. A parallel case, Murray v. Curlett, was brought by atheist Madalyn Murray and her son, objecting to a similar statute in Baltimore. As they were identical cases constitutionally, Murray was left to be decided by Schempp.

Writing for the Court, Justice Tom C. Clark reiterated the importance of religion in American culture, but arrived at the same finding as in Engel:

• The Constitution forbids state-sponsored religion;
• Prayer is religion;
• Therefore state (i.e. public school) sponsored prayer is impermissible.

The Court promulgated for the first time a test by which to compare potential infringements of the First Amendment Establishment Clause. To avoid constitutional infringement, legislation affecting religion must have "a secular legislative purpose and a primary effect that neither advances nor inhibits religion."

Justice Potter Stewart wrote in dissent: "A refusal to permit religious exercises thus is seen, not as a realization of state neutrality, but rather as the establishment of a religion of secularism, or at the least, as government support of the belief of those who think that religious exercises should be conducted only in private."

Justice Stewart contended, not only here but in Engel as well, that the Establishment Clause was only intended to prevent the establishment of an official state church, and that the Free Exercise Clause should protect the use of non-coercive religious exercises in schools and elsewhere. While Justice Stewart's opinions were never Court-shaping, they have contributed to the views of later members of the Court.