Mary Bills graduated with a bachelor's degree from the University of Wisconsin-Madison. She founded a Milwaukee, Wisconsin, school organization and served as president of the board of directors of the Metropolitan Integration Research Center (MIRC), an organization studying racial isolation in metropolitan Milwaukee, and on the Education Committee of the League of Women Voters of Greater Milwaukee before running for a seat on the Milwaukee School Board in 1985. She served as member of the school board from 1985-1997 and president of the school board from 1993-1995. Her involvement in education, and the school choice and voucher movements continued after her tenure on the board through participation in conferences and writing.
