This series contains correspondence between Elizabeth B. D. Sedgwick and her family and friends, including her mother Rhoda Dwight. The majority of the letters were written by Elizabeth Sedgwick to her friend Sarah Forbes.

This series, the largest in the collection, contains correspondence between Katharine Sedgwick Minot and 36 friends and family members. Correspondents include Katharine's daughter Alice W. Minot, aunt Catharine M. Sedgwick, son Charles Minot, father Charles Sedgwick, mother Elizabeth B. D. Sedgwick, cousin Elizabeth Ellery Sedgwick, aunt Frances Watson, brother-in-law Francis Minot, George Hillard, sister Grace A. S. Ashburner, son Henry Davis Minot, cousin Jane Sedgwick, grandfather Josiah Dwight, friend Julia Hamner, sister-in-law Julia Minot, sister-in-law Louisa Tellkampf Sedgwick, friend Lucy B. Channing, cousin Maria Banyer Sedgwick, cousin Mary Watson, grandmother Rhoda Edwards, son Robert S. Minot, uncle Robert Sedgwick, friend Sarah Forbes, aunt Susan A. L. Ridley, cousin Theodore Sedgwick III, son William Minot III, husband William Minot II, and brother William D. Sedgwick.

The majority of correspondence is between Katharine and her immediate family members. Correspondence with her daughter, Alice Woodbourne Minot, spans from Alice's childhood (age 7) to adulthood (age 32) and includes letters written during the Civil War. In 1861, Alice expresses her shock at hearing that Southerners were tying the wounded to trees and notes that her uncle, William D. Sedgwick, has left to fight. In 1862, she refers to a paper signed by the ladies in her town to compel the president to remove all incompetent and drunken officers.

Katharine's correspondence with her father, Charles Sedgwick, and mother, Elizabeth B. D. Sedgwick, primarily concerns family events and local news. Many letters were written while Katharine traveled with her aunt Catharine Maria Sedgwick. In 1842, she describes how she and her aunt met Charles Dickens at a dinner during his visit to the United States. Other correspondence between Katharine and Elizabeth relates to William D. Sedgwick's letters home during the Civil War and news that he was badly wounded in September 1862. Katharine also confides in her mother about her marriage and motherhood.

Correspondence between Katharine and her husband William Minot II spans a 40-year period, from before their marriage in 1842, to Katharine's death in 1880. Many letters are very personal in nature.

William Minot II shared many of the same correspondents as his wife Katharine Sedgwick Minot, and his correspondence covers many of the same topics. Included are letters discussing his and other family members' extensive travel, particularly within Europe. Correspondence between William and his brother-in-law William D. Sedgwick relates to the Civil War, including war strategy, troops, and the draft.

Correspondence between Elizabeth D. S. Rackemann and her niece Alice and nephews Henry and William contain discussions of family events and social activities. Included are many letters to and from her nephew Henry D. Minot, in particular.

This small series of correspondence includes letters related to Grace A. S. Bristed's education, including at a school in New York where she learned French, Italian, and piano, as well as letters discussing the approach of the Civil War and the relationship between the North and the South.

The majority of William D. Sedgwick's correspondence consists of letters to his mother, Elizabeth B. D. Sedgwick, during his service in the Civil War, 1861-1862. Included are detailed descriptions of events on the battlefield; military strategy; light, weather, and ground conditions; sights and sounds; lack of sleep; and his concern for family at home. In July 1861, he discusses his father-in-law Professor Tellkampf's disapproval of his continued service and belief that the cause of the Union is hopeless. This series also contains a certificate of his promotion to assistant adjutant general with the rank of major, signed by Abraham Lincoln in August 1862. In September 1862, William wrote to his mother informing her of his injury at the Battle of Antietam, from which he later died.

This series also contains condolence letters and other papers related to William's death.

This series consists of correspondence that cannot be incorporated into the other series of the collection, primarily letters between Katharine Sedgwick Minot and friends and family other than the individuals listed above. Included are letters written by Katharine in the 1830s to international pen pals, as well as letters by unidentified correspondents and letter fragments.

The series also contains poems, letter wrappers, sermons, a Valentine's greeting to Katharine Sedgwick Minot from 1838, and a list of persons present at Jane Sedgwick's christening in 1844. The latter portion of the correspondence centers on the children of William D. Sedgwick, Katharine Sedgwick Minot, and Elizabeth D. S. Rackemann.