To meet the new challenge, Father Mahoney rented a store at 1253 St. Nicholas Avenue between 172nd and 173rd Street and used it as a temporary chapel with the Holy Sacrifice of the Mass being offered there for the first time on Sunday, September 6, 1908.

Three months after the opening of the chapel, Father Mahoney instituted a regular Sunday School program, with a priest, two Sisters of Charity, and a number of lay teachers, to respond to the challenge of providing religious instructions for the children.

To assist Father Mahoney in carrying out his emerging program, the Reverend Walter D. Slattery was assigned priest of Incarnation.

Father Mahoney, well aware that the neighborhood continued to grow rapidly, determined that a complete school should be built.

[1] Archbishop John Murphy Farley laid the cornerstone for the new school on October 17, 1909, with Monsignor Michael J. Lavelle, Vicar General as preacher.

In the school's first years, the sisters lived at Saint Paul's Convent in Harlem and commuted to Washington Heights every day.

The additional two floors added to the building ten years prior was not enough to alleviate classroom overcrowding and the stress of teachers trying to educate classes crammed with students.

The Brothers' visible and effective influence was exercised throughout the school day and well into the night with daily and wide-ranging athletic programs.

Economic and political factors led to an influx of Cubans, Dominicans and families from Central and South America as well.

Monsignor Waterson accepted the challenge to integrate the newest residents into parish activities and encouraged families to enroll their children into the school.

Incarnation offered gym, art and music classes for each grade and students took advantage of a full-time guidance program.

Students participated in many diverse extracurricular activities, including yearbook, newspaper, Altar Boy Society, choral group, cheerleading, spelling bee, foreign mission activities, a school service program, art contest, talent show, author's day, and the production of an instructional television program.

Incarnation expanded its technological resources with Internet-based lessons, access to laptop computers, educational software, and wireless networking.