The Communist International which was created after the Russian Revolution was formed mostly from left-wing splits in the Socialist International. Many had ultra-left positions as a reaction to decades of the reformist leadership of the Socialist parties. Lenin used this book to educate the young cadres of the Comintern in the methods of Bolshevism and the relation between the class, the party, and the leadership. It is a masterpiece of Marxism, applying the basic tenets already outlined in the Manifesto: "The Communists do not form a separate party opposed to the other working-class parties; They have no interests separate and apart from those of the proletariat as a whole; They do not set up any sectarian principles of their own, by which to shape and mold the proletarian movement."

Read Left-wing Communism: An Infantile Disorder here