Karl Marx (1818-1883) was born in Trier to a German Jewish family that had converted to Christianity. As a student he was influenced by Hegel's dialectical philosophy but later reacted against his mentor's idealism and turned instead to the then new socialist movement. The Communist Manifesto (utilizing drafts by his friend Friedrich Engels) was written in a creative burst in Brussels for a German emigré society, the Communist League. After taking part in the failed revolutions of 1848, Marx fled to London, where he and his family lived in poverty alleviated only by Engels' financial help. For some years, Marx was a London correspondent for a New York newspaper. He spent most of his time, however, researching in the British Museum to document his theories of class struggle and the "internal contradictions" undermining capitalism. His works include: The Poverty of Philosophy, The Eighteenth Brumaire of Louis Bonaparte, The German Ideology, and A Contribution to the Critique of Political Economy.

Friedrich Engels (1820-1895) was born in Germany, the son of a textile manufacturer. After his military training in Berlin he became an agent of his father's business in Manchester and immersed himself in Chartism and the problems of the new urban proletariat created by the industrial revolution. In 1844, the year he met Karl Marx, he wrote The Condition of the Working Class in England. The pair's ideas were incorporated into The Communist Manifesto, although the actual writing was done by Marx. Not only did Engels provide Marx with money, but after 1870 spent much time assisting him in his research. After Marx's death Engels continued his work on Das Kapital, and completed it in 1894, a year before his own death. He also wrote The Peasant War in Germany, The Origin of the Family, and Socialism, Utopian and Scientific.

Martin Malia did his undergraduate work at Yale and earned his Ph.D. at Harvard. He has spent most of his teaching career at the University of California at Berkeley. His principal works include Alexander Herzen and the Birth of Russian Socialism, 1812-1855, The Soviet Tragedy: A History of Socialism in Russia, 1917-1991, and Russia under Western Eyes: From the Bronze Horseman to the Lenin Mausoleum.

Stephen Kotkin teaches history and international affairs at Princeton. His books include Armageddon Averted: The Soviet Collapse 1970-2000 and Uncivil Society: 1989 and the Implosion of the Communist Establishment. He formerly directed Princeton's Russian and Eurasian studies program (1996-2009) and served as the regular business book reviewer for the New York Times Sunday Business section (2006-2008). He founded and runs Princeton's Global History initiative.