The thesis outlines the history of the Gaelic language and culture in North-East Scotland which is defined as the old counties of Kincardine, Aberdeen, Banff, Moray and Nairn. After an introductory description of the North-East, the thesis explores the rise of Gaelic culture, the displacement of Pictish culture by Gaelic, and the dominant position of Gaelic in the North-East by the 12^th century as indicated in contemporary sources such as the Book of Deer. The thesis also describes the emergence of a linguistic and cultural frontier which endured between the 12^th and 19^th centuries, the association of Gaelic culture with the concept of the 'wild Scot', and the perception of the Gaidhealtachd as a region distinguished by language, dress and customs. In exploring these themes, particular areas have been commented upon, including, the church, law and administration and the burghs. Changing attitudes to Gaelic language and culture since the Reformation period have been outlined. The effect of Reformation politics on the North-East Gaelic communities, against a background of wider Scottish events, have been charted with frequent resort to contemporary sources such as the Minutes of the SSPCK, the Statistical Accounts and the Decennial Census Reports. The decline of the Gaelic language and culture in the North-East parishes has been traced from the late 17^th century down to the 20^th century, including some description of the last communities. Finally, an analysis of the Gaelic-speaking community in the city of Aberdeen has been made, focusing on the Gaelic chapel, the Celtic Society and Department at the University, and the evidence of the census for numbers of speakers.