Eastman visited until 1905, the Williams College and went to Columbia University two years later and worked there until 1911 as an assistant in philosophy and psychology. With his sister Chrystal Eastman, he lived in Greenwich Village. He helped 1910 at the founding of the Association Men's League for Women's Suffrage.
Eastman became a key figure in the left community of Greenwich Village.
In 1913 he published the study Enjoyment of Poetry. In the same year he became a writer for the magazine The Masses, which focused socialist philosophy and art.
1918 was The Masses under the 1917 Espionage Act passed by Congress. Eastman himself was charged twice, but acquitted both times. He and his sister founded in 1919 the journal The Liberator, which was acquired by financial problems in 1924 by the Communist Party of the United States. Eastman no longer worked after that for the sheet.
Eastman went to 1923 on a year-long trip to the Soviet Union to explore there, as Marxism would put into practice. He experienced the onset of the power struggles that culminated in Stalinism. After his return, he wrote several essays that criticized the system of the Soviet Union.
Despite this criticism, he held fast to his left-wing ideas. In the Soviet Union, he had built a friendship with Leon Trotsky. During Trotsky's exile in Mexico Eastman translated many of his works into English.
During the 1930s he wrote critical works on subjects of literature and was responsible for the completion and publication of the documentary From Tsar to Lenin in which he took on the role of the speaker. He was with Elena Krylenko, sister of the Soviet People's Commissar for Justice, Nikolai Vasilyevich Krylenko married.
1941 Eastman gave up his former communist and socialist ideas. He had been hired in this year's Reader 's Digest and remained the rest of his life in this position. He wrote articles critical of socialism and communism and actively supported Joseph McCarthy. Later he published a number of autobiographical works.
- Enjoyment of Poetry, 1913
- Child of the Amazons, 1913
- Journalism Versus Art, 1916
- Color of Life, 1918
- The Sense of Humor, 1921
- Leon Trotsky: The Portrait of a Youth, 1925
- Since Lenin Died, 1925
- Marx and Lenin: The Science of Revolution, 1926
- The Literary Mind: Its Place in on Age of Science, 1931
- Artists in Uniform, 1934
- Art and the Life of Action, 1934
- Enjoyment of Laughter, 1936
- Stalin 's Russia and the Crisis in Socialism, 1939
- Marxism: Is It a Science, 1940?
- Heroes I Have Known, 1942
- Enjoyment of Living, 1948
- Reflections on the Failure of Socialism, 1955
- Great Companions: Critical Memoirs of Some Famous Friends, 1959
- Love and Revolution: My Journey Through to Epoch, 1965
- Seven Kinds of Goodness, 1967