See Letters of Theodore Dwight Weld, Angelina Grimké Weld and Sarah Grimké 1822-1844, ed. by G. H. Barnes and D. L. Dumond (2 vol., 1934); biography by B. P. Thomas (1950); G. H. Barnes, The Antislavery Impulse, 1830-1844 (1933).
Weld played a role as writer, editor, speaker, and organizer. He is best known for his co-authorship of the authoritative compendium, American Slavery As It Is: Testimony of a Thousand Witnesses, published in 1839. Harriet Beecher Stowe partly based Uncle Tom’s Cabin on Weld's text and it is regarded as second only to that work in its influence on the antislavery movement.
While a student at Lane Theological Seminary in Cincinnati, Weld became a leader of the "Lane Rebels." This group of students held a series of slavery debates over 18 days in 1834 that divided the community. When the school's board of directors, including president Lyman Beecher, tried to prohibit the students from supporting abolitionism, Weld and a group of students left the seminary and were accepted by Oberlin College.
Weld married Angelina Grimké in 1838. From 1836 to 1840, Weld worked as the editor of the Emancipator. He also directed the national campaign for sending antislavery petitions to Congress and assisted John Quincy Adams when Congress tried Adams for reading petitions in violation of the gag rule.
In 1839, he and the Grimké sisters co-wrote the pivotal book American Slavery As It Is: Testimony of a Thousand Witnesses. As Weld used pen names for all of his writings, he is not as well known as many other notable 19th century civil rights advocates.
According to the Columbia Encyclopedia:
Many historians regard Weld as the most important figure in the abolitionist movement, surpassing even Garrison, but his passion for anonymity long made him an unknown figure in American history.
A member of the very notable Weld Family of New England, Weld shares a common ancestry with William Weld, Tuesday Weld, and others. Theodore Dwight Weld's branch of the familty never achieveed the wealth of their Boston-based kin.