Buchanan's primary purpose in writing the book was to present the history of his own family of Buchanan; his "A Historical and Genealogical Essay upon the Family and Surname of Buchanan" comprises over half the book. But he did as well provide histories of the following clans: MacDonald, MacDougal, MacNeil, MacLean, MacLeod, MacIntosh, MacPherson, Robertson, MacFarlane, Cameron, MacNauchtan, MacGregor, Colquhoun, Lamont, and MacAulay. He also included a transcription of the "Genealogies of the Chieff Clans of the Iles: collected by me, Sir Donald Monro, Heigh Dean of the Iles," which in turn gave early information about: Clan Donald, the Earls of Ross and Abbots of Ferne, and Clan Gunn, Clan Leod, and Clan Leandris (now surnamed Ross). The Buchanan section provides detailed information about the main branch of the family, as well as the collateral branches of Auchmar, Spittel, Arnpryor, Drumikill, Carbeth, Lenny, Auchneiven, Miltoun, Cashill, Arduill, Sallochie, and the septs of MacAuslan, MacMillan, MacColman, MacMaurice, MacAndeoir, MacChruiter, and MacGreusich. A full-name index enhances this fascinating look at Scottish history from its earliest period until the mid-1600s as seen through the development of family names.