This book reconstructs the efforts that were made to establish a missionary network between the two Irish Colleges of Rome, Ireland, and the West Indies during the seventeenth century. It analyses the process which brought the Irish clergy to establish two dedicated colleges in the epicenter of early modern Catholicism and to develop a series of missionary initiatives in the English islands of the West Indies. During a period of great political change in Ireland, continental Europe and the Atlantic region, the book traces how and through which key figures and institutions this clerical channel was established, while at the same time identifying the main obstacles to its development.