Manabendra Nath Roy was an Indian revolutionary and political activist and theorist. He was a founder of the Mexican Communist Party in 1919 and the Communist Party of India in 1920. At the second congress of the Communist International in 1920, Roy wrote the Supplementary Theses on the National and Colonial Question, which took up the question of the role of communists supporting and in organizing revolutionary anti-imperialist movements in the colonies. Roy broke with the Comintern in 1929 over Stalin’s “third period” policies, and later in life became a radical humanist. This talk will explore Roy’s development from nationalist to Marxist, and his political contributions.