In 1817, Fr. Edward Fenwick, O.P. offered the first Mass in Lancaster at the Garaghty home at the corner of Main and High Sts. In 1818/19, Fr. Nicholas Young, O.P., founded and named the parish St. Mary of the Assumption. A small frame building erected at the southeast corner of Chestnut St. and what is now Memorial Dr. served as the first church, dedicated Easter 1819.
5 June 2014 marked the 150th anniversary of the consecration of our 3rd and present church. In 2017 we remembered the 200th anniversary of the offering of the first Mass in Lancaster. Most recently, August of 2019 - 2020 was the bicentennial anniversary of the founding of our parish - again, another year of celebration was in order to commemorate this time in the life of our parish.
On 14 August 2022, The Most Rev. Earl K. Fernandes visited our parish to celebrate the solemnity of our patroness, Mary of the Assumption. Fernandes announced that the Apostolic See bestowed the title of basilica upon our church.