St. Mary of the Assumption Church and Parish has a long and glorious history. A few of the more noteworthy elements follow:

In 1817, Father Edward D. Fenwick, O.P. offered the first Mass at the home of Michael Garaghty in the original portion of the present Mumaugh Memorial at the corner of Main and High Streets.

In 1820, Father Nicholas D. Young, O.P., a nephew of Fr. Fenwick, founded and named the parish "St. Mary of the Assumption." A small frame building erected at the southeast corner of Chestnut and what is now Memorial Drive served as the first church. Dominican missionaries served the parish until 1834 when a permanent pastor, Father Thomas Martin, O.P. was appointed.

In 1839, Father Joshua Young became the first diocesan pastor. Recognizing the need for a larger church building, he purchased the property on the corner of Chestnut and High Streets. He arranged for the erection of a brick building that served as the church. Later the building was converted into the parish school and a residence for those who would teach in the school. The building was demolished to provide space for the current rectory.

In 1854, Father Henry lange determined that the second church building was too small for the rapidly increasing congregation and made plans for the present church building. That same year Guy Blair, general contractor, supervised the beginning of the construction. The stone and brick for the building came from Lancaster.

In 1859, Archbishop John Purcell laid the cornerstone. Shortly after that, with the outbreak of the Civil War and severe winter weather, diminished human and financial resources caused the work to come to a standstill. With the help of J. S. Snyder, wealthy parishioners, and with the perseverance of Fr. Lange, the construction was substantially completed within five years. However, Fr. Lange died a few months before the dedication of the building.

In 1864, Archbishop Purcell formally consecrated the church although the brick walls had not yet been plastered and the maze of posts and beams supporting the roof was still exposed. Part of the decorations of the building included the statues of Saint Boniface and Saint Patrick, the national patrons of the dominant ethnic groups that comprised the congregation.

In 1884, Father Nicholas Pilger was appointed pastor of St. Mary. During his tenure, he completed the plastering and painting of the interior of the church. In addition, he paid off the parish debt, and installed three bells, named Joseph, John and George, in the tower. The names reflect the donors: the St. Joseph Society, the Knights of St. John, and the Knights of St. George. Fr. Pilger's courage, pastoral style, and his temporal and spiritual leadership caused many from all denominations to mourn his death in December 1905.

In 1906, Father Jerome B. Mattingly became the pastor of St. Mary. Within a short time he undertook an ambitious and expensive building and remodeling program. Included in the effort was the construction of the parish school (now known as St. Mary West), the core of the convent, the rectory, an annex to the school and a janitor's residence. Fr. Mattingly engaged in much of the manual labor himself.

In 1909, Father Mattingly initiated several capital improvements related to the church. He supervised the construction of the "Assembly Room" beneath the church. With the help of Council 1016 of the Knights of Columbus, a magnificent pipe organ was installed which served the church until 1987. The present stained glass windows appeared in 1916 at the cost of approximately $450 each. Fr. Mattingly saw to the painting and lighting of the church even though the outbreak of World War I interfered with this project.

In 1923, Monsignor David Quiley was appointed pastor of St. Mary. During his long tenure, he built the high school building (now known as St. Mary East) which served high school and grade school students until the creation of William V. Fisher Catholic High School. His pastoral leadership guided the parish through the Great Depression and World War II. He retired in 1948.

In 1948, Father Julian Schaefer assumed the responsibilities of the pastor of St. Mary. He undertook a massive renovation and redecoration of the church building. In addition to the painting of the interior of the church, the principal features of the project included: sandblasting of the exterior of the church removing the red paint which had covered the bricks, and the construction of the porches on the side of the main entrance and the side chapels in what is now the quieting room and the vestry. Among the more controversial elements of the project were the placement of the mural of the Assumption in a gold-leaf reredos on the apse wall, the fabrication of a free standing marble altar composed in part from the existing altar rail, and the installation of new wood carved Stations of the Cross from Oberammergau.

In 1956, Bishop Ready assigned Monsignor Roland T. Winel as pastor of St. Mary. He guided the parish through the implementation of the initial reforms of the Vatican Council II. His efforts included the first celebration of Mass facing the people on an altar constructed and positioned more closely to the people. Msgr. Winel also raised over $700,000 in funds to purchase land for the new Lancaster parishes and to upgrade the school facilities at St. Mary.

In 1969, Father John Wolf became pastor of St. Mary. Within a short period and with the help of many generous and dedicated parishioners, he conducted a fund raising campaign for the construction of a new diocesan high school, William V. Fisher Catholic. Fr. Wolf is remembered by many parishioners for his dedication to Catholic education, his keen sense of humor and fiscal responsibility.

In 1981, Father William Dunn succeeded Fr. Wolf as pastor. He responded to the crisis of a broken and irreparable pipe organ by raising money to install a new pipe organ manufactured by Austin Organ Company, Hartford, Connecticut. He also installed the air-conditioning system in the church. His efforts of financial stewardship included the establishment of a bingo game to provide operating income for the church and school.

In 1990, Father Martin Weithman was appointed pastor of St. Mary. Upon the recommendation of the parish council, he initiated the RENEW program for spiritual growth and the annual celebration of the Patronal Feast of the Assumption. The parish council also convened a special CREAD committee (Church Repair, Enhancement, and Decoration) to work with Fr. Weithman in planning the restoration of St. Mary Church building. After nearly four years of research, study, dialogue with parishioners and planning, a special fund raising appeal, "Voices of Faith" was conducted for the benefit of the church restoration, the school endowment and the cemetery.

In 1994, the construction phase of the project began with the firm of Miles-McClellan as the general contractor and the firm Renouveau Design Inc. as architects. The objectives of the project were to enhance the finest Gothic features of the building and provide the proper spaces for the liturgical actions of the assembly. Special elements of the restoration include: the placement of the historic mural of the Assumption in an oak reredos similar to an earlier reredos at the turn of the century, the fabrication of a new pulpit consisting of the former bases of the side altars with an oak book stand, the erection of the Blessed Sacrament tower to house the original tabernacle of the church and, using pieces of existing altar rail, the creation of a new baptismal font providing for immersion. Two new reconciliation rooms were created and the lighting, electrical system and sound system were improved.

It is hoped that the restored church, dedicated by Bishop Griffin to inaugurate the 175th anniversary of the parish, will serve the liturgical needs of the parish family well into twenty-first century.