This chapter explores shifting and often contradictory dynamics which have manifested themselves in the relationship between Scottish Conservatism and Ulster Unionism. It provides a brief historical overview of this relationship which, it argues, has been highly salient in the consolidation of Conservatism as a political force in Scotland during the twentieth century, but which has become more ambiguous as understandings of ‘Union’, processes of secularisation, patterns of integration and differentiation, as well as the nature of centre-periphery relations in Northern Ireland and Scotland have increasingly diverged. The chapter also looks at how this relationship has continued to be reshaped into the twenty-first century by a potent mix of political forces which has included the Irish peace process, the Scottish independence referendum and Brexit.