The First Vatican Council Photograph Album contains 731 carte de visite albumen prints of First Vatican Council participants, and was likely created sometime during the council sessions that began on December 8, 1869 and ended on September 1, 1870. The participants were primarily European, though the United States was represented by 48 of 800 cardinals, patriarchs, archbishops, bishops, abbots, and religious superior generals in the sessions over the nine months. During the sessions, there were numerous discussions and disagreements as to the definition of papal infallibility, and the status of the bishops in relation to Pope Pius IX. In the end, two doctrinal constitutions emerged: Dei Filius (April 24, 1870), a shortened version of the schema on faith and reason, and Pastor aeternus (July 18, 1870), which defined the primacy and infallibility of the pope. The finding aid can be viewed at https://findingaids.lib.catholic.edu/repositories/2/resources/402, and a digital version of the collection can be viewed at https://cuislandora.wrlc.org/islandora/object/achc-vatican%3A1