Southwest historian and prominent civic and religious leader Cleofás Calleros (1896-1973) was born in Río Florido, Chihuahua, Mexico to Ismael Calleros and Refugio Perales de Calleros. The family immigrated to El Paso, Texas in 1902, when he was six years old. After graduating from school Calleros worked as a freight clerk for the Santa Fe Railway and as an accountant and private businessman. He was drafted into the United States Army and served in France during World War I. In the early 1920s he became a social worker and immigration specialist for the National Catholic Welfare Conference. As the author of numerous publications, articles, and speeches, he chronicled the history of the Southwestern United States, Mexico and the Catholic Church. The collection reflects his diverse interests and talents and his involvement with many civic, religious, and business organizations and institutions from about 1915 through 1973. The papers include correspondence, organizational minutes and reports, case files, photographs, scrapbooks, clippings, and literary manuscripts.