Adelphi also has centers in Downtown Brooklyn, Hudson Valley, and Suffolk County in addition to a virtual, online campus for remote students.

The academy was a private preparatory school located at 412 Adelphi Street, in the Fort Greene neighborhood of Brooklyn, but later moved to Clinton Hill.

It was formally chartered in 1869 by the board of trustees of the City of Brooklyn for establishing "a first class institution for the broadest and most thorough training, and to make its advantages as accessible as possible to the largest numbers of our population.

"[4] One of the teachers at the Adelphi Academy was Harlan Fiske Stone, who later served as the Chief Justice of the United States.

The college received its charter through the efforts of Timothy Woodruff, former Lieutenant Governor of New York and future first president of the board of trustees.

First Lady Eleanor Roosevelt presided over the opening of two federally funded residence halls on campus, in a speech entitled "The Challenge of Nursing for Young Women Today."

In 1946, after World War II ended, Adelphi reverted to a coeducational college and started admitting new students on the federal GI Bill.

In 1993, the Society of Mentors was established, giving students faculty advisors that they could consult on an as-needed basis to assist them in their studies.

University president Peter Diamandopoulos and the board of trustees were accused of neglect of duty, misconduct and failure to carry out the educational purposes of Adelphi.

[10] In August 2023, Adelphi relocated the Manhattan Center location to Downtown Brooklyn at 179 Livingston Street.

[24] Adelphi has partnerships with outside providers who offer study abroad opportunities to students in approximately 120 countries.

For semester and academic year direct exchanges with Adelphi partners, students may use 100% of their federal and institutional aid.

Adelphi student activities include academic interests, cultural and language clubs, sports and recreation, religious / Interfaith Center, arts organizations, volunteer opportunities, fraternities and sororities.

[29] Student resources include the Multicultural Center, SafeZones and SafeZone training, Gender-inclusive housing options, availability of designated all-gender restrooms, organizations and events (including Gender and Sexuality Alliance, Coming Out Day, Pride Week, Transgender Awareness Week), an Alumni Affinity group, mentoring, support and counseling.

The women's lacrosse team has won an NCAA Division II-record ten, including three consecutive National Championships in 2009, 2010, 2011 and back-to-back titles in 2014 and 2015; and most recently in 2019.

The honor is awarded to the institution that compiles the most total points from all of its programs competing in league championships.