This thesis considers the development of Evelyn Waugh's and Graham Greene’s Catholicism between 1928 and 1939. Focusing predominantly on Waugh’s and Greene’s novels, it investigates how their writings express Catholic ideas, as well how their faith informs their views of human nature, their political sympathies, and their criticisms of modern secular civilization. While it recognizes the important differences between Waugh’s and Greene’s thinking in this period (such as their diverging political sympathies and their uses of different forms and genres of writing), it also establishes some significant affiliations between their Catholic points of view. Both authors associate the increasingly secular condition of English society with themes of decay and disintegration, acknowledge the reality of Original Sin, and believe in a supernatural reality distinct from its earthly counterpart. The Introduction provides an overview of Greene and Waugh scholarship, noting that there is currently no critical study devoted to the topic of early affiliations between these authors’ Catholic principles. The first two chapters propose that the beginnings of Waugh’s and Greene’s Catholic perspectives can be detected in their early fiction. Chapter Three examines in relation to each other Waugh’s and Greene’s novels between 1930 and 1935. Chapter Four charts the development of their respective vantage-points in the period 1936-1938. The final chapter looks at the year 1939 and assesses the nature of these authors' Catholic views prior to the outbreak of the Second World War.