DSAers from a certain tradition think of themselves as being in the lineage of three socialist leaders: Eugene Debs who founded the Socialist Party of America, Norman Thomas who led it from the 1920s through the 1950s, and Michael Harrington, who led a majority of Socialist Party members to form the Democratic Socialist Organizing Committee in 1973.

Eugene V. Debs announced that he had become a socialist in 1897, when he was 42. Debs had already spent his lifetime as an active trade unionist and political activist in his home city of Terre Haute, Indiana. He had served six months in jail as a result of his forceful leadership during the great Pullman Strike of 1894. Many AFL unions can trace their beginnings to Eugene Debs' early career. After 1897, his devotion to American socialism and socialist idealism placed him at the center of many of the political and labor struggles of the early part of the century, including the founding of the IWW. He ran for President as the Socialist Party candidate five times, the last time from his jail cell where he was serving a sentence for encouraging Americans to resist induction into the Army during World War One.

Graduate of Princeton, Presbyterian minister Norman Thomas became a socialist and a pacifist at the age of 33, as a result of a long and gradual process. Already involved in social justice and political work in New York, Norman Thomas became America's First Socialist, continually advancing the causes of social justice. An inherently public man, his six presidential campaigns and five other attempts at public office were almost incidental to his lifetime of work in civil rights, labor, and peace groups, including the ACLU, NAACP, CORE and SANE. In his later years, Norman Thomas was often called America's Conscience, due to his stirring love of his country and its people. In a famous speech on the steps of the Capitol Building in 1968 Thomas proclaimed, "I come to cleanse the American Flag, not to burn it."

During Michael Harrington's four decades as America's leading socialist thinker, writer and speaker, he contributed to every progressive movement. One of the first of his twenty books, The Other America, is credited with spurring the Great Society anti-poverty programs. From his organizing with the student and civil rights movements in the 50's and 60's, to his leadership of the Democratic Socialist Organizing Committee (DSOC) and the Democratic Socialists of America (DSA) in the 70's and 80's, he consistently urged socialists to reach beyond isolation and build coalitions with labor and progressive groups in day-to-day struggles. As DSOC and DSA's representative to the Socialist International, he earned the respect, and the ear, of socialist leaders throughout the world. His death in 1989 did nothing to silence his thundering denunciation of injustice, for his voice lives on through us.