The story of the relationship between Ulster and Scotland during the seventeenth century has long been dominated by the flow of people and ideas from Scotland to the north of Ireland. This, however, belies the prominent role that Ireland had in the social and cultural history of the Western Isles and Highlands of Scotland during that century. This paper argues that of even greater importance to the resurgence of Catholicism in the Scottish Gaidhealtachd than a Rome driven Counter-Reformation were the financial support and personnel provided by Ulster Catholics. In the face of aggressive Stuart policies, Catholicism was rejuvenated and became an ideological justification for asserting traditional rights in the face of government sanctioned, Protestant blessed, incursions in the Western Isles. Moreover, in the face of historiography that has argued for the continual disintegration of ClanDonald throughout the seventeenth century, this article explores the ways the clans and their neighbours inspired, funded and facilitated the revival of Catholicism in the Gaidhealtachd.