This article explores the various factors that both encouraged Irish Presbyterian involvement in mission and shaped how they understood their missionary calling. It contributes to the recent growth of interest in the Protestant missionary movement and takes issue with the predominant interpretation of Irish Presbyterianism offered by David Miller who misunderstands the complex relationship between traditional Presbyterianism, evangelicalism and modernity. After an overview of the main developments between 1790 and 1840, a consideration of the influence of the Reformed theological tradition, eschatology and the growth of evangelicalism is followed by an examination of the Enlightenment, the expansion of the British empire and the Presbyterian sense of patriotic duty. Though various non-religious factors shaped Presbyterian attitudes to mission, it will be argued that their active involvement was a product of sincere religious conviction and an eschatological reading of the signs of the times.