... the Church, which is at home in all times and all places, and adapts itself to all; which blesses and fosters all healthy initiative, and has no fear of the progress, even the most daring progress of science, if only it he true science.1 Science, which consists in true recognition of fact, is never opposed to the truths of the Christian faith; in fact-as everyone who examines and meditates on the history of science is bound to admit-the Pontiffs, together with the Church, have never at any time failed to encourage the research work of learned men, also in the sphere of experimental science; this research work has, in turn, made a valid contribution to the defense of the treasure of heavenly truth entrusted to the Church.2 To date, scholars have examined precious little of the relationship between Catholicism and science in America.3 Those few researchers who have explored this field have limited their activity largely to studies of the controversy over evolution, Catholic women and health care, apologetics demonstrating how the Church has fostered rather than hindered science, or angry works on the history of sexuality, employing Catholicism as a slow-moving target.4 Indeed, the story of American Catholics and science, or the absence of a story, can be quickly characterized in a few pages, as Daniel Kevles did more than twenty years ago in his widely read The Physicists. Yet, reading Kevles leads to little satisfaction for one interested in going beyond superficialities, and in particular in placing science within a complex and dynamic social and cultural context.5 This essay focuses on the origins and early history of the Institutum Divi Thomae [hereafter referred to as the IDT or Institutum], thus describing one particularly rich episode illustrating the relationship between American Catholicism and science during the middle of the twentieth century. The IDT was established by the Archdiocese of Cincinnati in 1935; its faculty and students, while working in the area of cancer research, published hundreds of scientific and technical papers, developed a number of commercial products, and received considerable publicity in both the religious and secular press during the first two decades of its existence. However, with its gradual decline beginning in the 1950's and the closing of its doors by the 1980's, the IDT vanished without a trace from historians' radar screens. Yet if we are to understand more fully the IDT's accomplishments, the place of science within Catholic culture in twentieth-century America, and the science-- religion relationship in an operational institutional setting, this story becomes an important one. In the cultural context, the Institutum was an American Catholic response to both the modernist theological controversy and scientific materialism. Additionally on a more practical level, it served the need to train Catholic scientists in fundamental research. The aim of the IDT was to gain prestige at a time when American Catholics were being characterized as lacking in intellectual and scientific accomplishments. During the late 1920's and early 1930's, statistical studies indicated Catholicism's woeful lack of working scientists when compared to Protestant denominations and to perceptions of a decline in faith and an increase in moral decay.6 While the IDT met several specific needs of the Church, it also developed a distinctive humanitarian purpose reflective of its Christian origins-that of improving public health, most particularly in searching for a cure for cancer at a time prior to the involvement of big government and major research universities in scientific medicine. The IDT's struggle for self-definition, financial resources, and recognition resulted in new and useful products, newly trained scientists, and a number of unanswered historical questions. In June of 1935, the Archbishop of Cincinnati, the Most Reverend John T. McNicholas, O.P, played the leading role in creating the IDT As its founder, McNicholas left a significant imprint on the IDT's early mission and research strategies. …