Born on December 14, 1905 in Romanov, Russia, William Schneiderman was brought to the United States at the age of two by his parents. The family settled in Chicago where Schneiderman's father worked in the garment industry. The Schneidermans would later relocate to Los Angeles in the 1920s after William's father contracted T.B. While in Los Angeles, Schneiderman wrote in his autobiography that the "land of promise" had once again "mocked" his family (Schneiderman, Dissent on Trial, p. 15). It was this disillusionment and the poverty that he suffered as a child that helped to, in Schneiderman's words, develop a strong "working-class consciousness" (Ibid. p. 17) early in life. At age 16, Schneiderman joined the Young Communist League to begin his long career of political activism. Schneiderman also held a number of jobs while in Los Angeles during the Twenties. Letters of recommendation found in this collection indicate that he worked as a bookkeeper for the Upholstery Union No. 15, in a similar capacity for the National Biscuit Company, and as an office clerk for a local grocery. Despite working ten hour days, Schneiderman attended night classes at UCLA. While enrolled, Schneiderman actively opposed the compulsory ROTC program on campus. As a result of his activities, school officials classified him as a "non-citizen." The consequence of this change in status meant that Schneiderman had to pay significantly higher tuition as a non-resident in order to complete his education. The increase in fees proved to be too much for the already strapped Schneiderman and he was forced to drop out. He would finally receive his degree some forty years later.

Schneiderman's political convictions continued to have an impact on his personal fortunes. In 1925, he was fired from a job he had held for five years. The Simon Levi Company stated that Schneiderman was laid-off, "owing to some changes in our office work" (Simon Levi Co. letter of recommendation dated Nov. 28, 1925, Schneiderman Collection, box 2, folder 75). Schneiderman held that his dismissal was the result of being "fingered by the Red Squad." In 1927, Schneiderman's final citizenship papers came through and they would later become the source of some controversy. In 1930, Schneiderman was assigned by the Communist Party to become a district organizer in the New England area (a territory hard hit by unemployment). Schneiderman was transferred a year later to Minneapolis, where a number of party leaders had been indicted as a result of a "Red Scare." Serving once again as a district organizer, Schneiderman was also nominated as the Party's candidate for governor and received 5,000 votes. In 1935, Schneiderman spent a year in the Soviet Union and was deeply impressed with what he thought to be the future for all governments.

Returning to California, Schneiderman was appointed as state secretary for the Communist Party, a position he held until 1957. In 1939, the year of his marriage to Leah, the U.S. Justice Department moved to deport Schneiderman on the basis of his membership to the Communist Party during the time of his naturalization. Schneiderman's citizenship trial would eventually reach the Supreme Court where he was represented by Wendell Wilkie without fee. Schneiderman won the case and soon made headlines again, when in 1949 he and fourteen other communist leaders were indicted under the Smith Act (a list of the individuals indicted is included in the noteworthy individuals index at the end of this guide). With the eventual Supreme reversal of the Smith Act, Schneiderman resumed his active role within the Communist Party, and as state secretary he delivered a number of speeches at the various state and national conventions. In 1982, Schneiderman wrote his autobiography, Dissent on Trial, chronicling his struggles as a life-long political activist. William Schneiderman died on January 29, 1985.