The union's origins thus lie in the wave of militant and ambitious organizing precipitated by the CIO in the 1930s and 1940s, as the immigrant workers who had built and staffed Yale's new residential colleges began to organize themselves into an industrial union with the aid of CIO organizer John Clark and several sympathetic professors in Yale's Divinity School. For a detailed account of this story see Deborah Sue Elkin, Labor and The Left: The Limits of Acceptable Dissent at Yale University, 1920s to 1950s, unpublished Ph.D. dissertation, Yale University, 1995.