Maria Weston Chapman (July 25, 1806 – July 12, 1885) was an American abolitionist. She was elected to the executive committee of the American Anti-Slavery Society in 1839 and from 1839 until 1842, she served as editor of the anti-slavery journal The Non-Resistant.

Maria Weston was born in 1806 in Weymouth, Massachusetts to Captain Warren Richard Weston and Anne (née Bates) Weston. Eventually she had seven younger siblings—five sisters and two brothers. Though the Westons were not wealthy, they were well connected through her uncle's patronage. She spent several years of her youth living with family in England, where she received a robust education.

Weston returned to Boston in 1828 to serve as principal of a newly-founded, socially-progressive girls' high school. She left the field of education two years later to marry.

Maria and her husband Henry were both "Garrisonian" abolitionists, meaning that they believed in an "immediate" and uncompromising end to slavery, brought about by "moral suasion" or non-resistance. They rejected all political and institutional coercion—including churches, political parties and the federal government—as agencies for ending slavery. They did, however, support moral coercion that encompassed "come-outerism" and disunion, both of which opposed association with slaveholders. Gerald Sorin writes, "In [Maria's] nonresistance principles and in her 'come-outerism,' she was rigidly dogmatic and self-righteous, believing that 'when one is perfectly right, one neither asks nor needs sympathy.'"

Though Chapman came to the anti-slavery cause through her husband's family, she quickly and stalwartly took up the cause, enduring pro-slavery mobs, social ridicule, and public attacks on her character. Her sisters, notably Caroline and Anne, were also active abolitionists, though Maria is generally considered to be the most outspoken and active among her family. According to Lee V. Chambers, through their "kin-work", the sisters supported each other through family responsibilities in order to take their active public roles. The Chapmans became central figures in the "Boston Clique," which primarily consisted of wealthy and socially prominent supporters of William Lloyd Garrison. In 1835, Chapman assumed the leadership of the Boston Anti-Slavery Bazaar, which had been founded the previous year by Lydia Maria Child and Louisa Loring as a major fundraising event. She directed the fair until 1858, when she unilaterally decided to replace the bazaar with the Anti-Slavery Subscription Anniversary. Chapman said that the fair had become passé; she argued that the Anniversary—an exclusive, invitation-only soirée featuring music, food and speeches—was more au courant and would raise more funds than the bazaar. As described by historian Benjamin Quarles, through these years Chapman and other abolitionists became experienced in using "all the refined techniques of solicitation" in their fundraising for the cause of abolitionism.

In addition to her fair work, between 1835 and 1865, Chapman served on the executive and business committees of the Massachusetts Anti-Slavery Society (MASS), the New England Anti-Slavery Society (NEASS) and the American Anti-Slavery Society (AASS). Through these she was active in the petition campaigns of the 1830s. She wrote the annual reports of the Boston Female Anti-Slavery Society (BFASS) and published tracts to raise public awareness.^{[citation needed]}

For nearly 20 years, between 1839 and 1858, Chapman edited The Liberty Bell, an annual anti-slavery gift book sold at the Boston Bazaar as part of fundraising. The giftbook was composed of contributions from various notable figures: Longfellow, Emerson, Elizabeth Barrett Browning, Harriet Martineau, and Bayard Taylor, among others, none of whom was paid for their contributions aside from a copy of The Liberty Bell. She also served as editor to The Liberator in Garrison's absence, and was on the editorial committee of the National Anti-Slavery Standard, the official mouthpiece of the AASS. Chapman was also a member of the peace organisation, the Non-Resistance Society, which published The Non-Resistant.

Chapman was a prolific writer in her own right, publishing Right and Wrong in Massachusetts in 1839 and How Can I Help to Abolish Slavery? in 1855. Aside from these works, she published her poems and essays in abolitionist periodicals. In 1840 divisions between Garrisonians and the more political wing of the anti-slavery movement split the AASS and correspondingly the BFASS into two opposing factions. Maria, nicknamed "Captain Chapman" and the "great goddess" by her opponents and "Lady Macbeth" even by her friends, outmaneuvered the opposition. She took control of a resurrected BFASS, which from then on mainly focused on organizing the Boston bazaar as a major fundraiser for abolitionism.