Clapp was born in East Orange, New Jersey on April 10, 1910 to parents Alfred Chapin Clapp and Anna (Roth) Clapp. She had two brothers, future American politician Alfred C. and Oliver H. Clapp, and one sister, Lois Clapp Olds. In 1926 she graduated from East Orange High School and Wellesley College in 1930.
During and after World War II, she taught history at City College of New York, Douglass College, Columbia University, and Brooklyn College. Her doctoral dissertation at Columbia grew into the biography Forgotten First Citizen: John Bigelow published in 1947 and winner of the 1948 Pulitzer Prize for Biography or Autobiography.
While she was president of Wellesley College from 1949 until her retirement in 1966, the college's resources and facilities were expanded substantially. Clapp was a strong advocate of careers for women. She was elected a Fellow of the American Academy of Arts and Sciences in 1952.
After leaving Wellesley, Clapp served briefly as administrator of Lady Doak College, a women's college in Madurai, India, then as United States cultural attaché to India, then as minister-councilor of public affairs in the United States Information Agency until her retirement in 1971. The library at Wellesley is named for her.
- Forgotten First Citizen: John Bigelow (Little, Brown, 1947)
- The Modern University (Cornell University Press, 1950), edited by Clapp
- Margaret Clapp's Chapel Talks: a sampling (Wellesley College, 1980)
- List of covers of Time magazine (1940s) – Clapp was on the cover October 10, 1949
- Barbara Sicherman, Carol Hurd Green - Notable American Women: The Modern Period : a Biographical Dictionary, Volume 4
- Ohles, John F. (1978). Biographical Directory of American Educators. Connecticut: Greenwood Publishing Group. p. 268. ISBN 0-8371-9893-3.
- Leavitt, Judith A. American Women Managers and Administrators: A Selective Biographical Dictionary of Twentieth-century Leaders in Business, Education, and Government, p. 46. Greenwood Publishing Group, 1985. ISBN 9780313237485. Accessed September 11, 2016. "Clapp graduated from East Orange High School in 1926 and attended Wellesley College on a scholarship."
- Margaret Antoinette Clapp Encyclopedia of world Biography
- Wellesley Class of 1930 Archived 2010-12-15 at the Wayback Machine Wellesley College
- "Biography or Autobiography". The Pulitzer Prizes. Retrieved 2013-11-26.
- "Book of Members, 1780–2010: Chapter C" (PDF). American Academy of Arts and Sciences. Retrieved July 24, 2014.
- "The Margaret Clapp Library". Wellesley College Library.
- Lindheim, Burton (1974-05-04). "Margaret Clapp, 64, Dies; Wellesley Ex‐President". The New York Times. ISSN 0362-4331. Retrieved 2018-04-06.
- "Forgotten first citizen: John Bigelow". google.com.