The Critique of the Gotha Program is a document based on a letter by Karl Marx written in early May 1875 to the Social Democratic Workers' Party of Germany (SDAP), with whom Marx and Friedrich Engels were in close association. Offering perhaps Marx's most detailed pronouncement on programmatic matters of revolutionary strategy, the document discusses the "dictatorship of the proletariat," the period of transition from capitalism to communism, proletarian internationalism, and the party of the working class.