Apologetics:

Orthodoxy - A ringing defense of the faith

Heretics - A companion volume to Orthodoxy; the book is a critique of the philosophy of GKC's contemporaries

The Catholic Church and Conversion - A story of a man's conviction that the Catholic faith is right and all others are wrong.

Introduction to The Everlasting Man - Excerpted from The Everlasting Man

The Man in the Cave - Excerpted from The Everlasting Man

The God in the Cave - Excerpted from The Everlasting Man

The Everlasting Man - Chesterton's portrayal of the place of Christianity in the history of the world

The Runaway Abbot - Excerpted from St. Thomas Aquinas

St. Thomas Aquinas - Considered by some Thomist scholars to be the finest work on the saint

The Superstition of Divorce - On the modern attitude towards divorce, among other things.

Le Jongleur de Dieu - An excerpt from St. Francis of Assisi