Within a year of his arrival, Father Maguire learned of a marvelous opportunity. The Presbyterians had a fine English Tudor styled church for sale. Standing on the east side of Broadway, the church had been erected in 1853 in three industrious months from granite quarried locally. The building had served the Presbyterians well, its sole fault being that it had become too small. The Presbyterians had built their present church in 1869, and the old structure had been standing vacant for nearly four years when Father Maguire arrived in Irvington.
 
The parish had no money to buy the church, but Father Maguire did - $8,000, a sum that included part of his savings and the going away present that he had been given in New York. But when a direct offer was made to buy the church, reportedly for $9,000, it was refused. At the time, there was a young girl living in the parish, a Miss Annie Cromise who had converted to Catholicism while attending Mt. St. Vincent Academy, who persuaded her father, a non-Catholic New York merchant, to buy the church and then resell it to Father Maguire for only $8,000. The plan worked perfectly. The first Mass was said in the refurbished church on the feast of the Immaculate Conception, the new parish's patroness, December 8, 1874. Miss Cromise, having already proved herself indispensable, became the first organist and remained extremely active in all affairs of the parish until she moved away from the village.
 
Another equally important stalwart in the early days of the parish was Margaret Tewey. Miss Tewey was the only teacher at the high school, instructing in all of the arts and languages, while the principal handled mathematics and science. In addition, she directed the Sunday School until the parochial school was started in 1908, and in her spare time, devoted herself to her dead brother's family of six children, which she supported.
 
One of these six- Mary Tewey - remembers how, as a little girl of eight, she was roused out of bed while it was still pitch black to go to church at 5:00 a.m. to sing around the Christmas crib with the other children of the Sunday School. In the same year that the church was purchased, the members of the little parish built, largely with their own hands, the rectory that served as a home for the priests until October, 1974. The dark-red bricks were donated by a brickyard in Haverstraw and hauled free across the river in Captain Pateman's sloop. Neither the captain nor the owner of the brickyard was Catholic.