Aaron A. Abell, American Catholicism and Social Action: A search for social justice, 1865-1950 (Notre Dame, 1963)
Charles E. Curran, The Social Mission of the US Catholic Church: A theological perspective (Washington, 2011)
Patrick B. Lavey, "William J. Kerby, John A. Ryan and the Awakening of the Twentieth Century American Catholic Social Conscience, 1899-1919", Ph.D. diss., Univ. Illinois, 1986.
Mel Piehl, Breaking Bread: The Catholic Worker and the origin of Catholic radicalism in America (Tuscaloosa, 2006)
William D. Miller, A harsh and dreadful love: Dorothy Day and the Catholic Worker Movement (New York, 1973)
Douglas P. Seaton, Catholics and Radicals: The Association of Catholic Trade Unionists and the American Labor Movement from Depression to Cold War (Lewisberg, PA, 1981)
Look at Dorothy Day and colleagues in the Catholic Worker Movement in the 1930s, I believe, which is a precursor to Catholic Action and Liberation Theology. There is a thread of the convergence of Marxism and Christianity throughout, which Day confronted, and which came to fruition later in the 70s with Liberation Theology (Segundo & Gutierrez), although the latter is post your time frame. Interesting topic all around, particularly in the dissonance within the Vatican to activism despite the contention one might make that Christianity itself is an activist platform.