Karen Nussbaum is an American labor leader and founding director of Working America. Nussbaum was born in Chicago where her mother, Annette Brenner Nussbaum, was a publicist, and her father, Myron "Mike" Nussbaum, was an exterminator, actor, and director. Her parents were active in the anti-Vietnam movement and worked to bring speakers to their community of Highland Park in Chicago including Staughton Lynd. During this time, the family was also receiving hate mail from the local John Birch Society. She enrolled in the University of Chicago in 1968 but dropped out to move to Boston and work in the anti-Vietnam movement. In 1975, she earned a B.A. from Goddard College. While in Boston, she began working as a clerical worker at Harvard where she was exposed to inequalities in the workplace for female office workers.

Working America is the political organizing arm of the AFL–CIO. Its membership is made up of non-union individuals. It is the largest non-union workers' group in the United States, with a self-reported membership of 3.2 million individuals. Working America advocates for progressive policy issues. The organization recruits people in working-class neighborhoods on their doorsteps in an effort to persuade them to support labor-backed candidates at election time.