The Subiaco Cassinese Congregation is an international union of Benedictine houses (abbeys and priories) within the Benedictine Confederation. It developed from the Subiaco Congregation, which was formed in 1867 through the initiative of Dom Pietro Casaretto, O.S.B., as a reform of the way of life of monasteries of the Cassinese Congregation, formed in 1408, toward a stricter contemplative observance, and received final approval in 1872 by Pope Pius IX. After discussions between the two congregations at the start of the 21st century, approval was given by Pope Benedict XVI in 2013 for the incorporation of the Cassinese Congregation into its offshoot, the Subiaco Congregation. The expanded congregation was given this new name.