The Blaine Amendment was a failed amendment to the U.S. Constitution that would have prohibited direct government aid to educational institutions that have a religious affiliation. Most state constitutions already had such provisions, and thirty-eight of the fifty states have clauses that prohibit taxpayer funding of religious entities in their state constitutions.

The measures were designed to deny government aid to parochial schools, especially those operated by the Catholic Church in locations with large immigrant populations. They emerged from a growing consensus among 19th-century U.S. Protestants that public education must be free from “sectarian” or “denominational” control, while it also reflected nativist tendencies hostile to immigrants.

The amendments are generally seen as explicitly anti-Catholic because when they were enacted public schools typically included Protestant prayer, and taught from Protestant bibles, although debates about public funding of sectarian schools predate any significant Catholic immigration to the U.S. Thus, at the time of the Blaine amendments, public schools were not non-sectarian or non-denominational in the modern sense; nor were they completely secular.