Mount St. Alphonsus was built by the Redemptorist Congregation between 1904 and 1907. Redemptorist seminarians came to the Mount for their theology studies after spending 7 years in initial formation.

The seminary was a self-sufficient community — even the wine used for mass was made on the property. Over the years, neighboring sections of land were donated to the Redemptorists, bringing the original 235 acres to its current 400.

Due to the diminishing number of seminarians, students have been trained at the Washington Theological Union in Washington, D.C. since 1985. Since then the Redemptorist Retreat Ministry has grown steadily.