It was established in 1968 and had its main campus located in Oakdale, New York on the site of William K. Vanderbilt's mansion Idle Hour.

[2] After years of financial difficulties, frequently changing leadership, declining enrollment, and a failed search to find an academic partner, Dowling's accreditation was revoked by the Middle States Commission on Higher Education and the college ceased operations on August 31, 2016.

The wooden 110-room home was destroyed by fire April 15, 1899, while his son, William Kissam Vanderbilt II, was honeymooning there.

After Vanderbilt's death in 1920, the mansion went through several phases and visitors, including a brief stay during Prohibition by gangster Dutch Schultz.

Around that time, cow stalls, pig pens and corn cribs on the farm portion of Idle Hour were converted into a short-lived bohemian artists' colony that included figures such as George Elmer Browne and Roman Bonet-Sintas.

In 1955 Adelphi College began offering extension classes in Port Jefferson, Riverhead, and Sayville, New York.

[5] A shakeup occurred in June 1999 when Meskill fired five top-ranking college officials on the same day as a cost-cutting measure, after Dowling's debt had increased to $34 million and the school's credit rating had been downgraded.

[8] In August 2013, the Brookhaven Campus dormitory, bookstore, and cafeteria were closed due to the college's financial struggles.

In November 2015, Middle States required Dowling to show cause as to why the school's accreditation should not be revoked due to the college's finances, a final warning before such action would be taken.

In March 2016 Dowling announced that they had secured a partnership with Global University Systems, allowing the college to continue operating.

On that day, president Albert Inserra announced that negotiations had restarted and the motion to close the school was rescinded.

[17] A teach-out plan, required by Middle States, to help students transition to other institutions, was put into effect in partnership with Molloy College.

[18] On July 13, the board of trustees announced that they had failed to reach an agreement with Global University Systems, and the college would close on August 31, when Middle States would revoke its accreditation.

The campus also was the site of Dowling's sports complex, featuring a multi-purpose stadium, baseball and softball fields.

[27][28] The School of Aviation offered Bachelor of Science degrees in Aerospace Systems Technology, Aviation Management, and participated in the FAA Air Traffic Control Collegiate Training Initiative (AT-CTI) program, which is the primary source for hiring air traffic controllers.

[27] The School of Aviation maintained a fleet of aircraft which included nine Piper Warriors, an Arrow, and a twin engine Seminole.

The college was a member of the Division II level of the National Collegiate Athletic Association (NCAA), primarily competing in the East Coast Conference (ECC; formerly known as the New York Collegiate Athletic Conference (NYCAC) until after the 2005–06 school year) from 1989–90 to 2015–16 for all sports (with the exception of men's golf and field hockey, which competed as independents).