Drawing on archival as well as rich interview material, John F. Lyons examines the role of Chicago public schoolteachers and their union, the Chicago Teachers Union (CTU), in shaping the policies and practices of public education in Chicago from 1937 to 1970. From the union’s formation in 1937 until the 1960s, the CTU was the largest and most influential teachers’ union in the country, operating in the nation’s second largest school system. Although all Chicago public schoolteachers were committed to such bread-and-butter demands as higher salaries, many teachers also sought a more rigorous reform of the school system through calls for better working conditions, greater classroom autonomy, more funding for education, and the end of political control of the schools.Using political action, public relations campaigns, and community alliances, the CTU successfully raised members’ salaries and benefits, increased school budgets, influenced school curricula, and campaigned for greater equality for women within the Chicago public education system. Examining teachers’ unions and public education from the bottom up, Lyons shows how teachers’ unions helped to shape one of the largest public education systems in the nation. Taking into consideration the larger political context, such as World War II, the McCarthy era, and the civil rights movements of the 1960s, this study analyzes how the teachers’ attempts to improve their working lives and the quality of the Chicago public school system were constrained by internal divisions over race and gender as well as external disputes between the CTU and the school administration, state and local politicians, and powerful business and civic organizations.Because of the obstacles they faced and the decisions they made, unionized teachers left many problems unresolved, but they effected changes to public education and to local politics that still benefit Chicago teachers and the public today.