Clarence Richmond Thayer was a United Presbyterian Psychologist who spent his life studying and testing missionaries in attempts to predict the success of potential missionaries. Various boards and thousands of missionaries from Foreign Missions Conference of North America (FMCNA) participated in studies. The collection includes correspondence about studies as well as information about the donation of the collection to the Missionary Research Library; annotated copies of Dr. Thayer's PhD Thesis from the University of Pittsburgh; as well as records from the studies including results and data tables and the complete set of computer cards from the 1972 study.