This paper examines the origins of what may be termed the Holy See's film diplomacy by way of the Hollywood film industry. After the restoration of Vatican sovereignty through the Lateran Treaty in 1929, the Holy See sought ways to expand its influence beyond its limited temporal dominion. In an effort to navigate the ideological battles waged in the era of totalitarianism, the Holy See became an early proponent of popular media. Led by Eugenio Pacelli, first as Cardinal Secretary of State under Pope Pius XI in 1930, and then on succeeding him as Pius XII in 1939, the Holy See became a pioneer in utilizing nascent media for diplomatic purposes. Pacelli helped Pius XI usher in Vatican Radio in 1931. Then, upon his own ascension to the papacy, he welcomed the Vatican's first film documentary in 1939, became the first pope to star in a movie, for Pastor Angelicus in 1942, established the Pontifical Council for Social Communications in 1948 to guide Catholic involvement in the film industry, and a year later became the first pope to appear on television. As Pope, film emerged as a particular point of interest for Pacelli, who would give eight speeches on it between 1941 and 1949, and a further two encyclicals in the 1950s. This paper traces Pacelli's burgeoning interest in the film industry as Cardinal Secretary of State into his papacy through World War II. Utilizing the overlooked archival materials of Martin S. Quigley, Jr. and a variety of US sources, this paper uncovers the Holy See's initial connections to the Hollywood film industry and efforts among the Roman Curia to rein in and utilize US Catholics in the film industry for diplomatic purposes, leading up to and during the Second World War. As a result, this paper reveals a behind-the-scenes look into the film diplomacy that helped establish stronger relations between the Holy See and the United States, an association that would have significant and lasting effects in the Cold War.