The Miasnikov group formed part of what is called the Communist Left, on the same basis as other groups in Russia itself and in other parts of the world, particularly in Europe. The different expressions of this current found their origin in the reaction to the opportunist degeneration of the parties of the Third International and of soviet power in Russia. They represented a proletarian response in the form of left currents, like those that had existed previously faced with the development of opportunism in the Second International. We have published their complete Manifesto, previously unavailable other than in Russian state archives and for the first time in English, in several parts.