He studied an additional year at Andover, and there came under the influence of social reformer John A. Collins, before accepting a church in Loudon, New Hampshire.
Pillsbury's hostility to slavery led him into active writing and lecturing for the abolitionist movement and other progressive social reform issues.
[1] Pillsbury lectured widely on abolition and social reform, often in the company of fellow abolitionist Stephen Symonds Foster.
In 1865, Pillsbury broke with longtime associate William Lloyd Garrison over the need for continued activity by the American Anti-Slavery Society.
With feminist Elizabeth Cady Stanton, Pillsbury served as co-editor for the women's rights newsletter The Revolution, founded in 1868.