In 1904 Hagerty took a position as editor of a short-lived monthly publication of the American Labor Union called "Voice of Labor," through which he gave voice to his ideas about organization of workers in industry. It was in this capacity as a leading union magazine editor of the day that Hagerty was invited early in January 1905 as one of 23 industrial union activists from 9 organizations to a secret Chicago conference for the planning of a new national union. Hagerty help to draft the gathering's "Industrial Union Manifesto," a document which was to serve as an intellectual foundation stone for the establishment of the Industrial Workers of the World at a convention later that same year.