Quo Primum and De Defectibus
On the Roman Missal. Issued in the 16th century to safeguard the validity of the Mass. Should be read and studied by every Catholic truly concerned about the changes that have been introduced into the liturgy.

Mirari Vos
On Liberalism and Religious Indifferentism.

Ineffabilis Deus
On the Immaculate Conception. Apostolic Constitution defining the dogma of the Immaculate Conception. December 8, 1854. With study questions.

Qui Pluribus
On Faith and Religion. Raises the alert to the errors of the day day: liberalism, freemasonry, rationalism, pantheism, naturalism, Protestantism, and Communism.

Syllabus of Errors
The famous collection of the principal errors of our day condemned by Pius IX, concerning the moral law, marriage, liberalism, etc.

Aeterni Patris
On Restoration of Christian Philosophy. After writing in praise of philosophy and encouraging the pursuit of wisdom, Pope Leo gives a warning that true wisdom can only be found if God is the focus of study.

Custodi Di Quella Fede
Guardians of the Faith. Addressed to the Italian people, warning against the allurements and false promises of the freemasons.

Diuturnum
On Civil Government. A defense of authority for the security of the State and the common good; how authority comes from God; our Christian duty towards it.

Exeunte Jam Anno
On the Right Ordering of Christian Life. “It is a common complaint,” says Leo XIII, “that the age is barren of courageous men.” The solution? A Christian rule of life, as here outlined by the Sovereign Pontiff.

Humanum Genus
On Freemasonry. Is it “all right” to become a Mason? Read what the Popes have written about Freemasonry, its “power for evil,” and how we can have no compromise with it whatsoever. With discussion outline.

Laetitiae Sanctae
On the Rosary. As a complement to his many social encyclicals, the Pope of Social Justice offers the Rosary as a remedy for three great social evils: dislike of a simple life of labor, repugnance to suffering, and forgetfulness of eternal life.

Libertas Praestantissiumum
On Human Liberty. Clears up false notions of liberty being taught by the Church’s enemies.

Light in the Heavens
Thirty great encyclical letters of Pope Leo XIII (1878-1903). Covers a wide variety of topics, from doctrines of faith and moral application of Christian living to the solution to the evils of which Leo’s time saw but the beginnings.

Providentissiumus Deus
On Holy Scripture. The Church has always had great regard for the Sacred Scriptures and is anxious to have them widely read by her children. Explains her guidelines in this area. With study club outline.

Quamquam Pluries
On St. Joseph and the Rosary. The Pope urges his children to turn to the ever-Virgin Mother of God, and to that powerful model and protector, St. Joseph, to sustain us in the conflict against the enemies of the Faith.

Rerum Novarum
On Social Justice. The great encyclical of Pope Leo XIII on social justice — a masterpiece of eternal truths and timely guidance.

Tametsi Futura Prospecientibus
Our Divine Redeemer. Leo XIII here outlines the misfortune of those who fall away from and abandon the Christian faith and practice, giving as the remedy from such destruction a knowledge and acknowledgement of the rightful place of our Model and Redeemer in our lives.