She supported the work of her husband Horace Mann, an American education reformer and politician, as well as Henry David Thoreau, Nathaniel Hawthorne, and Sarah Winnemucca.

Mary Peabody began teaching at eighteen, first in Maine, then as a governess in Cuba, and she was a tutor and teacher in Massachusetts.

After her husband died in 1859, Mary Mann and her sister Elizabeth opened the first kindergarten school in the country, where they taught gymnastics, music, French, and social skills in addition to reading, writing, and arithmetic.

[5] Her sisters were Elizabeth, reformer, educator, and pioneer in establishing kindergarten schools and Sophia, painter and the wife of Nathaniel Hawthorne.

[4] Elizabeth Peabody operated a school from the family home, providing a classical education for boys and girls.

[2] In 1820, the Peabodys moved to a farm in Lancaster, Massachusetts, and daughter Elizabeth taught and ran the school beginning at age 16, based upon what she learned from her mother's tutelage.

Young Elizabeth taught from an enlightened perspective, helping her students build character, grow spiritually, and engage in discussions about school work.

[4] In 1825, Elizabeth and Mary lived in boarding house on Beacon Hill,[7] where they met a fellow boarder Horace Mann in 1832[4] or 1833.

[9] The sisters were Unitarians who embraced the Transcendentalism movement and supported fellow Transcendentalists Henry David Thoreau, Nathaniel Hawthorne, who married Sophia.

[4] In Estimate of Horace Mann, Mary wrote "I learned from him what night of the soul he had been nurtured and realized for the first time what a misfortune to mankind has been that creed which dishonors God and disenchants man.

"[11] In 1833, Mary went to Cuba, where she worked as a governess and looked after her sister Sophia, who went to the country to recuperate from some medical conditions.

[14] Elizabeth purchased foreign journals and books for her business, which was part bookstore, a lending library, and a place for scholars, liberal thinkers, and transcendentalists to meet.

His notes of the visits were the source material for his "Seventh Annual Report", and the recognition of what would be useful ideas to implement and what should be avoided.

[4][24] Mary Tyler Peabody Mann died in Jamaica Plain, Massachusetts, by February 11, 1887,[3][4] and she was buried at the North Burial Ground in Providence, Rhode Island.

[4] Mary Peabody left home at eighteen to teach school in Hallowell, Maine, where her sister Elizabeth had taught.

[25] Returning to Boston from Cuba, Mary moved in with her brother George in March 1835, and found employment tutoring an Italian student.

[26] At that time Elizabeth taught at Amos Bronson Alcott's experimental Temple School, and Mary substituted for her briefly.

[4] There is only one reference to Mary: "On 1 May 1843, Mr. Mann was again married, and sailed for Europe to visit European schools, especially in Germany, where he expected to derive most benefit.

"[8] Her writings, especially those on the kindergarten system, with her sister, Elizabeth Palmer Peabody, are distinguished for vigor of thought and felicity of expression.

[3] The collaboration of Mary and Elizabeth included promoting the speaking career of Sarah Winnemucca Hopkins, the first Native American woman known to secure a copyright and to publish in the English language.

Elizabeth Peabody commented, "The story is fiction; but the principal characters and the most important incidents are real—it was this that made the author keep back the book from publication till all were dead… It was the merest accident that the work was not published before my sister's death, as she so earnestly desired it should be.