The Callahan Library serves the Long Island Campus community as well as the SJNY Online students. The McEntegart Library serves the Brooklyn Campus community.
The Callahan Library serves the Long Island campus of the St. Joseph's College community. The original library at this location was located in the main classroom building, O'Connor Hall. The current library building opened in the Fall of 1989, and is named in memory of Sister Virginia Therese Callahan, the first Vice-President and Dean of the Suffolk Campus.
On October 2, 1916 St. Joseph’s College opened at 286 Washington Avenue with eight faculty members. At the time, there was no permanent librarian and faculty members serviced the library in their spare time.
By 1924, the College had moved to 245 Clinton Avenue (Tuohy Hall) and the library's collection numbered 6,050 volumes in that building. When the college was granted a permanent charter in 1929, accredited librarians were employed and they oversaw the collection in that space until the library moved again to 265 Clinton Avenue (Lorenzo Hall) in 1936.
By the early 1960s, the library had outgrown its space in Lorenzo Hall. On September 12, 1964, the library moved to its current location at 222 Clinton Avenue and the building was named McEntegart Hall, after Bryan J. McEntegart, a former Bishop of Brooklyn and President of the Board of Trustees from 1958-68.