Haas was born in Racine, Wisconsin, and was ordained a priest for the Archdiocese of Milwaukee in 1913. He attained his Ph.D. in sociology at the Catholic University of America, where he studied under such notable social thinkers as John A. Ryan and William Kerby. He subseqently taught at St. Francis Seminary and at Marquette University, and published important works in the field of Catholic social teaching. In the 1920s and 1930s he worked on state and national labor relations boards, becoming one of the Department of Labor's most active strike mediators. After his appointment as bishop of Grand Rapids, he continued to be involved in government activity, in the area of civil rights.