Mount St. Alphonsus Seminary (later Mount St. Alphonsus Retreat Center), located in Esopus, New York, was an American Roman Catholic seminary founded in 1907 by the Congregation of the Most Holy Redeemer, more commonly known as the Redemptorist Fathers and Brothers. It operated as a seminary until 1985, after which it became a center for meetings and spiritual retreats for the people of the Hudson Valley in New York. In 2012, the Mount ceased operations and was leased to the Bruderhof Communities who use the building for their Mount Academy.