What is Communist Anarchism? is an introduction to the principles of anarchism and anarchist communism written by Alexander Berkman. First published in 1929 by Vanguard Press, it has been reprinted many times, often in partial or abbreviated versions, under many titles such as Now and After, What Is Anarchism? or The ABC of Anarchism.

Because of its presentation of anarchist philosophy in plain language, What is Communist Anarchism? has become one of the best-known introductions to anarchism in print. Anarchist Stuart Christie wrote that What is Communist Anarchism? is "among the best introductions to the ideas of anarchism in the English language". Historian Paul Avrich described it as "a classic" and wrote that it was "the clearest exposition of communist anarchism in English or any other language".