Upon the church's rebuilding and re-dedication, the Society of Jesus strengthened their ties to this parish by founding the school, which was encouraged by the Dominicans at St. Vincent Ferrer and the Paulist Fathers at St. Paul the Apostle.

After various building material strikes delayed completion, the six-story Renaissance Revival style steel-framed school opened on December 17, 1900,[4] and was formally dedicated by Michael A. Corrigan, Archbishop of New York, on February 11, 1901.

"[6] The Latin inscription on the first floor chapel bow's blind window panel (with segmental pediment) of the Park Avenue facade reads "SANCT IGNATIO / DE LOYOLA / PATRI LEGIFERO / SOCIETATIS JESV / QVI VBICVMQVE / GENTIVM / IN SPEM RELIGIONIS / ET CIVITATIS / ADOLESCENTES MORIBUS / ET BONIS ARTIBVS / IMBVIT / AEDES HAE / DEDICANTVR" which translates: "To Saint Ignatius Loyola / Founder of the Society of Jesus / who for the good of Church and State / everywhere / has stored the minds of youth / with virtue and learning / these buildings are dedicated.

The stained glass was by Louis C. Tiffany and above Schroen's white marble altar was a canopied statue of Our Lady of Lourdes by the New York-sculptor Joseph Sibbel.

[9] The six-story gymnasium and rectory at 43–63 East 83rd Street was built in 1953 to designs by architects Eggers & Higgins at a reported cost of $800,000.