The Revolution Betrayed: What Is the Soviet Union and Where Is It Going? is a book published in 1936 by the exiled Soviet leader Leon Trotsky. This work analyzed and criticized the course of historical development in the Soviet Union following the death of Vladimir Lenin in 1924 and is regarded as Trotsky's primary work dealing with the nature of Stalinism. The book was written by Trotsky during his exile in Norway and was originally translated into Spanish by Victor Serge. The most widely available English translation is by Max Eastman.

Lev Davidovich Bronstein, better known as Leon Trotsky, was a Russian revolutionary, Soviet politician, journalist, and political theorist. He was a central figure in the 1905 Revolution, October Revolution, Russian Civil War, and the establishment of the Soviet Union. Alongside Vladimir Lenin, Trotsky was widely considered the most prominent Soviet figure and was de facto second-in-command during the early years of the Russian Soviet Republic. Ideologically a Marxist and a Leninist, his thought and writings inspired a school of Marxism known as Trotskyism.