The Catholic Encyclopedia, or the Old Catholic Encyclopedia, is an English language encyclopedia. It was published by The Encyclopedia Press. The first volume appeared in March 1907. It was completed in April 1914.

The encyclopedia was designed for the Roman Catholic Church. It does not include information which has nothing to do with the Church. It explains matters from the point of view of the official Catholic doctrine, as it was during the time of Pope Pius X. It tells the accomplishments of Catholics and some others in nearly all intellectual and professional pursuits. These include artists, educators, poets and scientists.