The Joshua Coffin Papers include correspondence, family genealogies, legal documents, church records, military records, and town records for Newbury, Massachusetts. This collection has been arranged into three series.

Series I. Newbury Vital Records includes original documents collected by Joshua Coffin while researching his book A Sketch of the History of Newbury, Newburyport and West Newbury. This series has been arranged into two subseries. Subseries A. Volume 1 and Subseries B. Volume 2 include similar records that were previously removed from bound volumes. In an effort to maintain this arrangement, the documents have been arranged by subject matter within their original volumes. Records within these two subseries include church records such as petitions for new parishes, divisions within churches, and lists of attendees. There are also legal documents created by individuals living in Newbury, such as deeds, last wills and testaments, marriage settlements, attorney appointments, and insurance policies. Military records are included in these volumes as well, such as muster rolls, enlistment papers, regimental orders, and equipment returns. Town of Newbury records include warrants, financial records, boundary line disputes, and notices to assemble. All records within these two subseries are arranged chronologically within subject folders. Selections of material found in both subseries were published in the Essex Institute Historical Collections (EIHC), Volume 35. The bracketed page number next to a document identifies the original location in the bound volume, as cited in the EIHC.

Series II. Correspondence and Research includes personal correspondence, collected Newbury history materials, Anti-Slavery writings and publications, membership documents for local historical societies, and town clerk records. This series includes handwritten copies of documents that aided Coffin in his research, such as lists of births and deaths in Newbury and a list of the original grantees of Newbury. Additional research material includes handwritten copies of Sebastian Ralle's work among the Indians in 1720; Samuel Rolfe's journal from 1750; Caleb Haskell's journal with the Continental Army in 1775; and a description of a tornado at sea in 1841. There is also a bound journal that Coffin labeled "Collections from Ancient Records," which includes additional handwritten copies of original documents. Correspondence between Coffin, fellow genealogists or and Newbury locals, reveal Coffin's working methods and areas of historical interest. The material in this series is arranged chronologically within subject folder.

Series III. Genealogies include genealogies of Newbury families created by Joshua Coffin and his correspondents. This material is arranged alphabetically by family name. Correspondence and lists of multiple family names, along with complied notebooks of families appear at the end of the series.