In politics, integralism, integrationism or integrism is an interpretation of Catholic social teaching that argues the principle that the Catholic faith should be the basis of public law and public policy within civil society, wherever the preponderance of Catholics within that society makes this possible. Integralism is anti-pluralist, seeking the Catholic faith to be dominant in civil and religious matters. Integralists uphold the 1864 definition of Pope Pius IX in Quanta cura that the religious neutrality of the civil power cannot be embraced as an ideal situation and the doctrine of Leo XIII in Immortale Dei on the religious obligations of states. In December 1965, the Second Vatican Council approved and Pope Paul VI promulgated the document Dignitatis humanae–the Council's "Declaration on Religious Freedom"–which states that it "leaves untouched traditional Catholic doctrine on the moral duty of men and societies toward the true religion and toward the one Church of Christ". However, they have simultaneously declared "that the human person has a right to religious freedom," a move that some traditionalist Catholics such as Archbishop Marcel Lefebvre, the founder of the Society of St. Pius X, have argued is at odds with previous doctrinal pronouncements.

Traditionalist Catholicism is a movement that emphasizes beliefs, practices, customs, traditions, liturgical forms, devotions and presentations of teaching associated with the Catholic Church before the Second Vatican Council (1962–1965). Traditionalist Catholics particularly emphasize the Tridentine Mass, the Roman Rite liturgy largely replaced in general use by the post-Second Vatican Council Mass of Paul VI.