Part of the Harvard Faculty of Arts and Sciences, HES offers both part-time, open-enrollment courses, as well as selective undergraduate (ALB) and graduate (ALM) degrees primarily for nontraditional students.

Established by then-university President A. Lawrence Lowell,[4][5] HES was commissioned to extend[6] education, equivalent in academic rigor to traditional Harvard programs, to non-traditional and part-time students, as well as lifelong learners.

According to Harvard's current guidelines, students are required to achieve a minimum 3.0 GPA in degree-credit coursework in order to matriculate.

Matriculated students have additional benefits such as convocation, graduation, cross-registration, teaching assistant, faculty research aid, and supervised senior thesis or research paper; they also, as students of Harvard University, have access to the full resources and the broader academic environment of Harvard.

"[11] It was designed to serve the educational interests and needs of the Greater Boston community,[12] particularly those "who had the ability and desire to attend college, but also had other obligations that kept them from traditional schools.

In the early years, a commission composed of several Boston area schools ran the courses, though it was largely a Harvard-run program.

[19] Several years after his retirement, President Lowell wrote that the Extension courses "have given a service to the public ... which seems to me of the utmost importance.

[8] From 1971 to 2014, the school offered an Associate of Arts in Extension Studies (AA), the equivalent of a two-year degree.

'"[26] While the school retains "Extension Studies" in official degree titles, transcripts reflect students' area of academic concentration.

In order to earn an academic degree, students must complete a minimum number of on-campus-only credits at Harvard.

[47][50] Ropes, the school's first dean, said that "our aim will be to give the young people of Boston who have heretofore been prevented from securing a college education the same instruction they would receive were they undergraduates at Harvard.

[57] Students who successfully complete the program are eligible for sponsorship and a committee letter of support in their applications to medical school.

New Englanders could go to college six nights a week at 7:30 in their living rooms simply by tuning into courses on psychology, world history, and economics.

The radio courses proved to be so successful that when the television station WGBH went on the air in October 1951 they began broadcasting an Extension class every weekday at 3:30 and 7:30.

[63] Students who watched the courses on television could attend six "conferences" and take a mid-term and a final exam at Harvard in order to gain credit for the class.

[40] To be eligible to apply to the Extension School's degree programs, students must "earn [their] way in" by passing the Test of Critical Reading and Writing Skills as well as completing two or three designated admission classes with a B or better.

Extension students may earn the Dean's List Academic Achievement Award upon graduation based on a high GPA (at least 3.5 for ALB, 3.8 for ALM).

[75] The expository writing class is known as a "gatekeeper course" as it will typically "determine whether [students] are prepared for the intensive and demanding curriculum.

[75] In addition to a concentration, degree candidates have the option to pursue one of twenty "fields of study" (similar to majors).

[79] Students must also hold a "high school diploma or its equivalent [which] must have been earned at least five years prior to enrolling in any ALB degree-applicable courses.

"[80] Students applying for degree candidacy must complete three 4-credit liberal arts courses at Harvard with at least a B grade in each, and maintain a minimum 3.0 cumulative GPA.

[82] Application to a graduate degree program requires an accredited bachelor's degree (or foreign equivalent), passing the Test of Critical Reading and Writing Skills, the completion of two or three designated pre-admission courses with grades of B or higher, and a cumulative grade-point average of 3.0.

In addition, several programs require supplemental application materials; for instance, Creative Writing and Literature ALM candidates must submit original manuscripts.

[83] Students who meet these criteria are then eligible to submit an application for admission into the graduate degree programs (ALM).

A student who fails to earn a grade of B after twice enrolling in the proseminar course—often considered a "gatekeeper" course—will be denied admission indefinitely.

[85] Alpha Sigma Lambda, the national honor society for nontraditional students, has a Harvard chapter.

[72] Harvard Extension School degree students can work as faculty aides and research assistants for instructors at the university.