It was an emended and expanded version of an earlier work in two volumes entitled Kirchliches Handlexikon (Munich, 1904–1912).
The editor's goal was to create a modern summa theologiae, i.e. a reference work that would cover all aspects of Catholic teaching, life and practice.
The second edition of the work was prepared between 1957 and 1968 by Josef Höfer and Karl Rahner.
At that time, the Catholic Church was experiencing drastic changes, culminating in the Second Vatican Council.
Topics covered include all aspects of Catholic theology, doctrine, history and practice, as well as other subjects related to the Roman Catholic Church and Roman Catholicism in general.