|Harriett M. Stone Lothrop|
Margaret Sydney 1920
June 22, 1844|
New Haven, Connecticut
|Died||August 2, 1924(aged 80)|
|Pen name||Margaret Sidney|
Margaret Sidney was the pseudonym of American author Harriett Mulford Stone Lothrop (June 22, 1844–August 2, 1924). In addition to writing popular children's stories, she ran her husband Daniel Lothrop's publishing company after his death. After they bought The Wayside country house together, they worked hard to make it a center of literary life.
Harriett Mulford Stone was born in New Haven, Connecticut, in 1844. The daughter of New Haven architect, Sidney Mason Stone, she was “brought up in an atmosphere of culture and learning enhanced by free access to her father’s large library.”  From early girlhood she “delighted in creating imaginary people”.  She was educated at seminaries near her home and graduated from Miss Dutton’s School at Grove Hall in New Haven in 1862.  While a student there “she displayed such mental alertness, combined with retentive memory and a great imaginative and poetic talent that she was marked for future success.”  She traveled extensively in the United States, and began creating literary compositions early in life. According to a Hartford Courant article, “she wrote constantly but destroyed manuscripts”. 
She published nothing until 1878 when, at the age of 34, she began sending short stories to Wide Awake, a children's magazine in Boston. Two of her stories, “Polly Pepper's Chicken Pie” and “Phronsie Pepper's New Shoes,” proved to be very popular with readers. Daniel Lothrop, the editor of the magazine, requested that Stone write more.
The success of Harriett's short stories prompted her to write the now-famous “Five Little Peppers” series. This series was first published in 1881, the year that Stone married Daniel Lothrop. Daniel had founded the D. Lothrop Company of Boston, who published Harriett's books under her pseudonym, Margaret Sidney.
Harriett and Daniel may have both had an interest in history and in famous authors. In 1883, they purchased the house in which both Louisa May Alcott and Nathaniel Hawthorne had lived. Nicknamed The Wayside, the house is located in Concord, Massachusetts. The year after Harriett and Daniel moved into the house, Harriett gave birth to their daughter, Margaret, at the age of 40.
Daniel Lothrop died on Friday, March 18, 1892, when Harriett was 48 and their daughter was just 9 years old. There was a gap in the release of the “Five Little Peppers” books from 1892 to 1897, while Harriett continued to run the publishing company Daniel founded. Eventually, she sold the company, which later became Lothrop, Lee & Shepard Co. It continued to publish Harriett's books under the name Margaret Sidney when Harriett resumed writing the “Five Little Peppers” series.
She died at the age of 80.
Harriett was involved with Daughters of the American Revolution. In 1895, Harriett formed a children's group of a similar vein called Children of the American Revolution. This group, organized “for the training of young people in true patriotism and love of country", still exists today.
She loved travelling overseas, but spent many winters in California where the climate was more agreeable.
Alongside her writing career, Stone had a deep interest in historical homes and buildings and worked hard to preserve them. These include:
- The Wayside, where she lived with her family
- Orchard House, which belonged to the Alcott family and was next door to the Wayside
- Grapevine Cottage, where Ephraim Wales Bull developed the Concord grape
- The Tolman House in Dorchester, Massachusetts built during the colonial period
In later years, Stone's daughter Margaret Lothrop championed to have her childhood home, The Wayside, declared a National Historic Landmark. It was made so in 1963.
Harriett eventually wrote over 30 books. Besides the “Five Little Peppers” series, these included:
- So as by Fire (Boston, 1881)
- Half Year at Bronckton (1882)
- The Pettibone Name (1883), a novel of New England life
- What the Seven Did (1883)
- Who told it to Me (1884)
- Ballad of the Lost Hare (1884) From the Collections at the Library of Congress
- The Golden West (1885)
- How they Went to Europe (1885)
- Hester, and other New England Stories (1886)
- The Minute-Man (1886)
- Two Modern Little Princes (1887)
- Dilly and the Captain (1887)
- St. George and the Dragon (1888)
- The Judges' Cave; Being a Romance of the New Haven Colony in the Days of the Regicides, 1661 (1900)
- A Little Maid of Concord Town, on a patriotic theme
- A Little Maid of Boston, also on a patriotic theme
- The National cyclopaedia of American biography, Vol 8 (1898) James T. White & Co., New York
- James, Edward T., et al. (Eds.) Notable American Women 1607-1950: A Biographical Dictionary, Harvard University Press: Boston, 1971, p. 431.
- Lothrop, Margaret M., The Wayside: Home of Authors, American Book Company, New York, 1940, unpaged.
- Miss Dutton’s School at Grove Hall, List of Teachers and Pupils 1847-1863, on file at the New Haven Colony Historical Society Library.
- Hartford Courant, April 6, 1924, p. 3D
- One or more of the preceding sentences incorporates text from a publication now in the public domain: Wilson, James Grant; Fiske, John, eds. (1900). "Lothrop, Harriett Mulford". Appletons' Cyclopædia of American Biography. New York: D. Appleton.
- Hartford Courant, April 6, 1924, p. 3D
- “A Guide to the Margaret Sidney (Harriet Mulford Stone Lothrop) Papers,” George A Smathers Library, University of Florida