The years just after World War II were a time of transition for Irish America, as returning G.I.’s made their way into the middle class using education benefits, and the country rebounded from the previous decade’s depression. Once concentrated urban Irish-American neighborhoods began to break up as the children raised there moved ‚”up‚” and out to the suburbs. This paper will focus on one novel written during that time period, Harry Sylvester’s Moon Gaffney (1947). This controversial novel was deemed anti-clerical by many members of the Catholic Church, both lay and religious. Others saw it as speaking the truth, and trying to get their beloved Church to look closely at its flaws. What Sylvester does through Moon Gaffney is challenge the Church to live up to its teachings regarding the poor. It sets those working for the Catholic Worker movement and for labor unions against priests, bishops, and other Irish Americans moving into the upper class, who are more interested in gathering and protecting wealth than helping the poor and working people. He shows young, socially conscious people struggling with their conscience as they risk tearing away from the Church that they love. The fear of radicalism, and the conflation of pro-labor activity with communism by those in positions of power, jeopardizes families, friendships, and careers. This paper will examine Moon Gaffney as a novel written at a time of transition, that challenges Irish-American Catholics to decide who they were going to be going forward in this country.