Encyclopedias, Almanacs, Transcripts, and Maps
- Ant Thrushes (Formicariidae)
- Antarctic Treaty (1961)
- Antarctica Project
- Anteaters (Myrmecophagidae)
- Antelopes, Cattle, Bison, Buffaloes, Goats, and Sheep (Bovidae)
- Anthesteria
- Anthony of Padua
- Anthozoa (Anemones and Corals)
- Anthropology, Ethnology, and Religion
- Anthroposophy
- anticline
- Anticult Movements
- Anura (Frogs and Toads)
- Apache Religious Traditions
- Aplacophora (Aplacophorans)
- Apocalypse: An Overview
- Apocalypse: Jewish Apocalypticism to the Rabbinic Period
- Apocalypse: Medieval Jewish Apocalyptic Literature
- Apocatastasis
- Apodiformes (Swifts and Hummingbirds)