This thesis is in two parts. Part One, Captain Simon Fraser: his life and Airs, provides an introduction to traditional Scottish Gaelic music and song related to Airs (his major musical publication), and investigates his family's and his own military and farming careers, and their possible relevance to the melodies he published. It also examines how Fraser collected, published, and promoted Airs and similar projects, in part through his unpublished correspondence with Sir Walter Scott, and with the Highland Society of Scotland, with other supporting documentation. Part Two, Gaelic songs from Captain Simon Fraser's Airs, is a collection of the author's editions of songs created from marrying edited melodies from the collection of the Gaelic poems associated with them through their titles, or similar information. This is intended to prove that the music in Airs, although originally set instrumentally, can provide valid musical sources for mainly eighteenth-century Scottish Gaelic songs. The collection is prefaced by two introductions. The first discusses Fraser as a musician and editor, as well as some of the difficulties which may arise when dealing with music of his kind. The second introduction explains how the editorial notes are presented, what elements of the song will be discussed and explains this editor's working methods. These notes, which utilise scholarly apparatus, may be found in Part Two, after the songs, which are interleaved with facsimiles of Fraser original versions, for ease of study. The results of the research found in Part One is a detailed picture of Fraser as a soldier, a farmer, and a collector and publisher of traditional Gaelic melodies, alongside new insights into the workings of patronage at the end of the 'long eighteenth', through Fraser's unpublished correspondence with the Highland Society of Scotland, and with Sir Walter Scott. Part Two provides practical examples of the suitability of Fraser's art music settings as a basis for the production of versions of Scottish Gaelic songs for which there is no comparable historic source.