Harry Wellington Laidler was an American socialist writer, magazine editor, and politician. He is best remembered as executive director of the League for Industrial Democracy, successor to the Intercollegiate Socialist Society, and for his close political association with perennial Socialist Party Presidential nominee Norman Thomas. He also served a two-year term on the New York City Council.

Louis Waldman was a leading figure in the Socialist Party of America from the late 1910s and through the middle 1930s, a founding member of the Social Democratic Federation, and a prominent New York labor lawyer. He was expelled from the New York State Assembly in 1920 during the First Red Scare.