Max Eastman (1883-1969) was born in 1883. He became an activist for women's issues and was an early supporter of the Left Opposition. In 1912 he was asked to take over editorship of The Masses and under him the journal moved further to the left. In 1918, after The Masses had to cease publication, Eastman started with other radical writers to publish The Liberator, a magazine with similar intentions to The Masses, and remained with the magazine until 1924, when The Liberator was taken over by the Communist Party. Max Eastman died in 1969.

Floyd Dell (1887-1969), born in 1887, was only sixteen when he joined the Socialist Party. In 1914 he moved to New York to help Max Eastman edit The Masses. In 1918 Dell went on to publish The Liberator (1918-24), a very similar magazine to The Masses. After the war Dell published the best-selling autobiographical novel, Moon-Calf (1920) as well as writing for the left-wing magazines such as the New Masses (1924-39) Dell wrote several non-fictional works including Upton Sinclair (1927), Love in the Machine Age (1930) and an autobiography, Homecoming (1933). He died in 1969.

John Reed(1887-1920) was born in 1887 and worked as a journalist. He joined the Communists while reporting the Revolution in 1917.John Reed is the author of Ten Days that Shook the World. In 1919 he helped form the Communist Labor Party in the US. 1920 John Reed died in the Soviet Union.

Louis Untermeyer (1885-1977), born in 1885, published his first book of poetry, First Love in 1911. Louis Untermeyer held left-wing political views and was an editor for The Masses. In 1950 he became a panelist on the television programme, What's My Line. Like many other left-wing artists he became a victim of McCarthyism. In 1956 Untermeyer was awarded a Gold Medal by the Poetry Society of America. He died 1977.

Mary Heaton-Vorse (1874-1966), born in 1874, was strong supporter of women's suffrage and involved in the American suffrage campaign. She worked for The Masses until it ceased publication in 1917. Over the next few years Heaton-Vorse produced articles on child labor, infant mortality, labor disputes and working class housing. She also published several books, including Men and Steel (1921) and A Footnote to Folly (1935) and more than 400 articles and stories in most of America's leading journals. Mary Heaton Vorse died in 1966.

Art Young (1866-1943), born in 1866, had his first work of art accepted by the Judge magazine at the age of seventeen. Soon after his first success, Young moved to Chicago, where he was offered work with the Chicago Daily News and the Chicago Inter-Ocean. When Piet Vlag started The Masses, in 1910, he asked Young to join him. Over the next few years Young published his cartoons in The Masses as well as The Liberator (1918-24) or Good Morning (1919-21). He also worked for the Saturday Evening Post, the Nation, New Masses and the New Leader. Art Young continued to produce politically committed cartoons until his death in 1943.

Boardman Robinson (1876-1952) was born in 1876. and worked as acartoonist for the New York Times and the New York Tribune.
Boardman Robinson was a strong supporter of woman suffrage and during the First World War he had a large number of cartoons published in The Masses. After The Masses turned into The Liberator Boardman also became a contributing editor of the The Liberator. Boardman Robinson died in 1952.

George Bellows (1882-1925), born in 1882, studied art at the New York School of Art under Robert Henri, who was the leader of what became known as the Ashcan School. From 1911 on he began contributing pictures to The Masses. For The Masses he produced several anti-war drawings including such as the powerful attack on Woodrow Wilson and his Espionage Act, Blessed are the Peacemakers.
In 1919 Bellows started working at the Chicago Art Institute and he also illustrated novels including several by H. G. Wells. George Bellows died 1925.