Seventeenth-century English men and women, caught in the upheaval of the Civil War, sought to understand what it was to be English and sought to grasp England's proper role in the world. One of the ways in which they did this was through their encounters with other people. The Irish had a long history of interaction with the English, but in the middle of the seventeenth century their role in defining Englishness became acute. Late Tudor and early Jacobean commentaries on Ireland had stressed the superiority of English culture while acknowledging some virtues of Ireland and its people that would make it amenable to beneficial transformation by the English. In the middle of the century, occasioned by the events of the 1641 uprising, this ameliorative view of the Irish gave way to the view that English and Irish were incompatible. Earlier studies have emphasized the role of religion in the discordant relationship between the two peoples in the seventeenth century. This essay maintains that the shift in attitude had as much to do with ethnicity as it did with religion and considers the central role of John Temple and his treatise The Irish rebellion in changing English attitudes on both a national and local level. The study suggests that Temple's view became the dominant one for more than 200 years because of the demographic changes within the Irish community in London and puritan concerns about a godly community that occurred at the time Temple set forth his ideas.