ST. MARY'S MISSION CHURCH IN FISHKILL was erected in 1861 at the beginning of the Civil War. For ninety-two years, St. Mary's was the mission of St. Joachim's Parish in Beacon. In February, 1953, a St. Mary's Parish Association was formed. This Association petitioned the Archdiocese for a separate Parish. On June 29, 1953, this new Parish was established with Monsignor Francis McKeon as its first Pastor. The building of the new school proceeded rapidly. The new School Auditorium was opened for masses on eve of the Assumption Feast of our Blessed Mother Mary, August 14, 1955. In September of that same year the school was opened with the enrollment of 125 pupils and staffed by the Sisters of the Presentation of the Blessed Virgin Mary whose Mother House is St. Joseph's in Newburgh. The School has grown continuously since then. Plans were being made to add a kindergarten plus an extra room since it has outgrown the present facilities. In addition, to meet the needs of a growing and lively Parish, plans were also underway to construct a Parish House and improve parking facilities.

In 1964, after eleven years of zealous service as the Pastor of this Parish, Msgr. McKeon was made Pastor of St. Ursula's Church in Mount Vernon. On the 14th of August, 1964, Msgr. Bernard Fleming was appointed Pastor. He proceeded with the planning of the new Church with energy and enthusiasm. The ground breaking for the new Church took place on June 6, 1965 and the consecration and first Mass were celebrated on Saturday, December 9, 1967. The latter years of Msgr. Fleming's service were troubled by various illnesses. He retired to the Mary Manning Walsh Home in February of 1981. After serving there to the best of his priestly ability, he died in November, 1982. In December of that same year, Father Charles P. Quinn, who had been Associate Pastor and later Administrator at St. Mary's, was appointed Pastor.

In September, 1994, Fr. Charles Quinn moved to St. Stanislaus Parish in Pleasant Valley and was succeeded by Fr. Joseph Martin who was the coordinator of the Parish Mission Team of New York Archdiocese. Fr. Martin became a Monsignor when the Pope visited the Archdiocese of New York in October 1996. He is the current Pastor of St. Mary, Mother of the Church.