The papers cover six centuries worth of family and estate papers of the Forbes, the Stuart Forbes, and the Trefusis families. Alexander de Forbes (c.1380-1448) was created the 1st Lord Forbes around 1440, the Lords Forbes of Pitsligo were descended from Sir William Forbes, brother of Alexander. The title was created in 1633 for Alexander Forbes (d.1636). His descendant Alexander Forbes, 4th Lord Forbes of Pitsligo (1678-1762) forfeited his estates following his support for the Jacobites in the 1745 uprising. Sir William Forbes, 6th Baronet of Monymusk and Pitsligo (1739-1806) whose grandmother was the sister of the 4th Lord Forbes of Pitsligo, became a successful banker in Edinburgh and worked to recover the former possessions of his ancestors. In 1783 he laid out the village of New Pitsligo. Fettercairn House came into the family's possession through the marriage of William Forbes, 7th Baronet of Monymusk and Pitsligo (1773-1828), to Williamina Belsches Stuart (d.1810), the daughter of Sir John Stuart (c.1752-1821), who was MP for Kincardineshire between 1797 and 1806, and owner of the estate. Following the death of Sir John Stuart Hepburn Forbes, 8th Baronet of Monymusk and Pitsligo (1804-1866), the baronetcy passed to his nephew William Stuart Forbes (1835-1906) owing to the lack of a male heir. The 8th Baronet's daughter, Harriet Williamina Hebpurn Forbes (1835-1869) married Charles Henry Rolle Hebpurn Stuart Forbes Trefusis, 20th Baron Clinton (1834-1904). Their son Charles John Robert Hepburn Stuart Forbes Trefusis, 21st Baron Clinton (1863-1957), continued to take an interest in Fettercairn and was Convener of Kincardineshire County Council.

The family papers contain personal and banking correspondence of Sir William Forbes, 6th Bart, including some papers relating to James Boswell for whom Forbes acted as part-exectuor following Boswell's death. The correspondence of Sir William Forbes, 7th Bart, includes letters on the growing Forbes family art collection and the acquisition of art in Italy. The general family papers also contain lectures and research notes of James David Forbes (1809-1868) physicist, and brother of Sir John Stuart Hepburn Forbes. Some of the research notes and lectures of James's son George Forbes (1849-1936) astronomer and electrical engineer also form part of the collection.

Among the estate papers are a series of factors letters sent to Sir John Stuart and to Sir John Stuart Hepburn Forbes concering the management of the Fettercairn estate. There are a series of wet letter press books covering the physcial management of the estate from 1870 until 1936.A series of account books cover the financial management for the same period. There is a small group of papers which covers the management of estates in Pitsligo from the 17th to the 19th century. Following the establishment of New Pitsligo in 1783 there are a series of papers covering its operation, however, these date mostly from the 19th century.

The printed works formerly owned by the families are mostly clean copies, although several of them indicate previous owners and also contain either small amounts of annotations or letters and documents tipped in to the volumes. There are a substanial number of works of both James and George Forbes.