Most Holy Trinity Church began as St. Thomas Church, built in 1867. It was a mission of Blessed Sacrament church in New Rochelle N.Y..The mission became a parish in 1874, then the present church was built by 1885 and renamed Most Holy Trinity. Most Holy Trinity was originally known as the church of St. Thomas when it stood at the corner of Spruce Street and Boston Post Road. The founder Reverend Thomas McLaughlin was a pastor in New Rochelle and visited the Mamaroneck area once a month by wagon to attend to any parochial details. During his tenure, 12 churches were built in the original territory of his jurisdiction and Mamaroneck was one of them. It was an old tradition that father McLaughlin visited Mamaroneck once a month, saying mass in private homes and in the "Old Red House" which stood at the bank of the Mamaroneck River near Prospect Avenue, in the rear of the Hook and Ladder Company. During this time, baptisms, confirmations, first communion and marriages of the Mamaroneck Catholics took place in New Rochelle at a church called Saint Matthews, the first Catholic Church in New Rochelle. This church was later named Blessed Sacrament. One of the parish's early pastors, Rev. Isidore Meister, was responsible for the construction of a new stone church building. Parishioners helped collect and save money and the project was completed in 1886. The new building was dedicated on Sunday, August 15, 1886 by Archbishop Corrigan. Since then, succeeding pastors worked to add on to the parish with a school, convent, rectory and gymnasium. Most Holy Trinity Parish School, originally erected in 1928, was run by the Sisters of Charity of New York. At its inception the Sisters, living at Saint Vincent's Retreat Center, traveled to and fro by surrey driven by the church custodian, Patrick Murphy. They commuted for 28 years until a convent was built on site in 1914. The Franciscan Sisters of Hastings also taught at the school. The school closed in 1987. On November 2, 2014 the Archdiocese of New York announced as part of its "Making All Things New" round of church closures that Most Holy Trinity Parish would be merged with the Parish of Saint Vito also located in Mamaroneck, New York. As of August 2015, the church is part of the newly formed parish of Most Holy Trinity-Saint Vito with no regularly scheduled masses occurring at Most Holy Trinity Church. The parish is served by the Knights of Columbus, Council 2247.
The first pastor of Holy Trinity was Father Christopher A. Farrell. Other former pastors include: Bishop Joseph P. Donahue, 1913 to 1924, who eventually became vicar general of the archdiocese of N.Y., Father Francis P. Duffy, who served there in the early part of the twentieth century, and also Father Thomas Kelly, 1942 to 1952, who had been the confessor of Rose Hawthorne, daughter of Nathaniel Hawthorne and the founder of the Servants of Relief for Incurable Cancer. More recent pastors have included Msgr. Thomas Darby, 1969 to 1976, and Msgr. John Mulroy, 1976 to 1989. Father Joseph F. Irwin was appointed to Mamaroneck in 1989. He was succeeded by Father Robert P. Henry in 2012 who served until the merger in 2015. Father Joseph Tierney is the current Administrator of Most Holy Trinity-Saint Vito Parish.
