Early yearsMasquers Club was formed by actors fed up with the grueling work hours at the Hollywood studios. This was one of the major concerns which led to the creation of the Screen Actors Guild in 1933. Another was that the Academy of Motion Picture Arts and Sciences, which at that time arbitrated between the producers and actors on contract disputes, had a membership policy which was by invitation only.
A meeting in March 1933 of six actors (Berton Churchill, Charles Miller, Grant Mitchell, Ralph Morgan, Alden Gay, and Kenneth Thomson) led to the guild's foundation. Three months later, three of the six and eighteen others became the guild's first officers and board of directors: Ralph Morgan (its first president), Alden Gay, Kenneth Thomson, Alan Mowbray (who personally funded the organization when it was first founded), Leon Ames, Tyler Brooke, Clay Clement, James Gleason, Lucile Webster Gleason, Boris Karloff (reportedly influenced by long hours suffered during the filming of Frankenstein), Claude King, Noel Madison, Reginald Mason, Bradley Page, Willard Robertson, Ivan Simpson, C. Aubrey Smith, Charles Starrett, Richard Tucker, Arthur Vinton, Morgan Wallace and Lyle Talbot.
Many high-profile actors refused to join SAG initially. This changed when the producers made an agreement amongst themselves not to bid competitively for talent. A pivotal meeting, at the home of Frank Morgan (Ralph's brother, who played the title role in The Wizard of Oz), is what gave SAG its critical mass. Prompted by Eddie Cantor's insistence, at that meeting, that any response to that producer's agreement help all actors, not just the already established ones, it took only three weeks for SAG membership to go from around 80 members to more than 4,000. Cantor's participation was critical, particularly because of his friendship with the recently-elected President Franklin Roosevelt. After several years and the passage of the National Labor Relations Act, the producers agreed to negotiate with SAG in 1937.
Actors known for their early support of SAG (besides the founders) include Edward Arnold, Humphrey Bogart, James Cagney, Dudley Digges, Porter Hall, Paul Harvey, Jean Hersholt, Russell Hicks, Murray Kinnell, Gene Lockhart, Bela Lugosi, David Manners, Fredric March, Adolphe Menjou, Chester Morris, Jean Muir, George Murphy, Erin O'Brien-Moore, Irving Pichel, Dick Powell, Edward G. Robinson, Edwin Stanley, Gloria Stuart, Lyle Talbot, Franchot Tone, Warren William, and Robert Young.
 Blacklist yearsIn October 1947, a list of suspected communists working in the Hollywood film industry were summoned to appear before the House Committee on Un-American Activities (HUAC), which was investigating Communist influence in the Hollywood labor unions. Ten of those summoned, dubbed the "Hollywood Ten", refused to cooperate and were charged with contempt of Congress and sentenced to prison. Several liberal members of SAG, led by Humphrey Bogart, Lauren Bacall, Danny Kaye, and Gene Kelly formed the Committee for the First Amendment (CFA) and flew to Washington, DC, in late October 1947 to show support for the Hollywood Ten. (Several of the CFA's members, including Bogart, Edward G. Robinson, and John Garfield later recanted, saying they had been "duped", not realizing that some of the Ten were really communists.)
The president of SAG – future United States President Ronald Reagan – also known to the FBI as Confidential Informant "T-10", testified before the committee but never publicly named names. Instead, according to an FBI memorandum in 1947: "T-10 advised Special Agent [name deleted] that he has been made a member of a committee headed by Mayer, the purpose of which is allegedly is to 'purge' the motion-picture industry of Communist party members, which committee was an outgrowth of the Thomas committee hearings in Washington and subsequent meetings . . . He felt that lacking a definite stand on the part of the government, it would be very difficult for any committee of motion-picture people to conduct any type of cleansing of their own household". Subsequently a climate of fear, enhanced by the threat of detention under the provisions of the McCarran Internal Security Act, permeated the film industry. On November 17, 1947, the Screen Actors Guild voted to force its officers to take a "non-communist" pledge. On November 25 (the day after the full House approved the ten citations for contempt) in what has become known as the Waldorf Statement, Eric Johnston, president of the Motion Picture Association of America (MPAA), issued a press release: "We will not knowingly employ a Communist or a member of any party or group which advocates the overthrow of the government of the United States by force or by any illegal or unconstitutional methods."
Under President Reagan the Screen Actors Guild require a loyalty oath for membership that included swearing that you have never been a member of the communist or socialist parties. AFTRA had a less strict oath, but Actors Equity refused to give in to McCarthy and the Red Fear.
None of those blacklisted were proven to advocate overthrowing the government – most simply had liveral, Marxist or socialist views. The Waldorf Statement marked the beginning of the Hollywood blacklist that saw hundreds of people prevented from working in the film industry. During the height of what is now referred to as McCarthyism, the Screen Writers Guild gave the studios the right to omit from the screen the name of any individual who had failed to clear his name before Congress. At a 1997 ceremony marking the 50th anniversary of the Blacklist, the Guild's president made this statement:
Only our sister union, Actors Equity Association, had the courage to stand behind its members and help them continue their creative lives in the theater. ... Unfortunately, there are no credits to restore, nor any other belated recognition that we can offer our members who were blacklisted. They could not work under assumed names or employ surrogates to front for them. An actor's work and his or her identity are inseparable. Screen Actors Guild's participation in tonight's event must stand as our testament to all those who suffered that, in the future, we will strongly support our members and work with them to assure their rights as defined and guaranteed by the Bill of Rights.
—Richard Masur, Hollywood Remembers the Blacklist