This dissertation examines Scottish unionist political thought and intellectual history in the period from 1885-1886 to 1965. It provides an analytical examination of unionist positions examining such areas as political history, ecclesiology, sectarianism, historiography and unionist-nationalist sentiment. It contextualises unionist thought within Scotland's history and offers findings based on both archival and primary sources research along with a thorough background of historiography. It both contextualises and examines the complexities of Scottish unionism during this vital period between the Liberal Party's split over Irish Home Rule until the reorganisation of the Scottish Unionist Party in 1965. It illuminates the spectrum of unionist discourse during this period and demonstrates the complexities of Scotland's constitutional and cultural relationship with the rest of the United Kingdom.