What is the difference between the Free Exercise Clause and the Establishment Clause?

Both clauses live in the same sixteen words of the First Amendment: “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.” They restrain the same actor — government — but point in opposite directions. The Establishment Clause stops government from promoting, funding, or endorsing religion; the Free Exercise Clause stops government from burdening or punishing someone for practicing their own religion. A government prayer read aloud in a public school is an Establishment Clause problem; firing someone for wearing a religious head covering at work is a Free Exercise Clause problem. The two can even pull against each other — accommodating one person's religious practice can look, to a challenger, like government endorsement of that religion. The Free Exercise Clause's meaning shifted sharply in Employment Division v. Smith, 494 U.S. 872 (1990), where the Supreme Court held that a neutral, generally applicable law — one not written to target a specific religion — does not violate free exercise even if it burdens a religious practice, in that case Native American Church members' sacramental use of peyote. This replaced a stricter "compelling interest" test the Court had used since Sherbert v. Verner (1963), which required government to justify any burden on religious practice with a compelling reason. Congress responded to Smith by passing the Religious Freedom Restoration Act in 1993, restoring the compelling-interest standard for federal law, though Smith's neutral-and-generally-applicable rule still governs how state laws are reviewed under the Free Exercise Clause. This is general information, not legal advice.