The 1st Regiment Massachusetts Volunteer Heavy Artillery Association Records includes by-laws, correspondence, rosters, record books, member surveys, sketchbooks, journal transcripts, and newspaper clippings. The collection has been arranged into two series.

The 23rd Regiment Massachusetts Volunteer Infantry Association records include meeting minutes, correspondence, reunion programs and invitations, scrapbooks, photographs, and newspaper clippings created and collected by elected officers and members of the 23rd Regiment Association. The collection has been arranged into three series.

Byron Gilman papers contain a daily account of Gilman's life from September 16, 1861 until September 27, 1864.

The Everett Guard Records include a club roll of the members of the Everett Guard. The collection has been arranged into one series.

The Herbert E. Valentine Papers includes scrapbooks, diaries, correspondence, sketches, photographs, printer's blocks, newspaper clippings, and books created by Valentine both during and after the Civil War.

The Massachusetts Volunteer Militia Records includes orderly books, rosters and enlistment records, quartermaster accounts, guard report books, general orders and brigade orders, muster rolls, company descriptive books, and correspondence. This collection has been arranged into twenty-two series based on regimental distinctions.

The William Cogswell papers document Cogswell's career as a politician and military officer.