The thesis treats the controversy over the naturalization of foreign Protestants from the Restoration of Charles II to the accession of George III. Chapter I summarizes the law of nationality and naturalization, describes the procedures of naturalization and denization, and surveys the legislative history of the many bills for a general naturalization that were introduced from the Restoration to the 1750s. Chapters II, III, and IV treat the economic literature of the controversy over naturalization, and the theories of population that underlay it, in the period from 1660 to 1710. The nature, origins, and evolution of the arguments for the encouragement of immigration are described. Chapters V and VI tell the story of the migration of about 13,000 Germans who came to England in 1709 from the Rhenish Palatinate and other areas of the Rhine Valley. The Palatine migration offers a striking illustration of the pitfalls of the attempt to increase England's population by encouraging large-scale immigration. The influx of the Palatines provoked a sufficient outcry to dampen the naturalization movement, and Chapter VII treats the opposition to naturalization and the hostility to immigrants throughout the period. It presents many examples of opposition, particularly that of the City of London, and examines both attitudes to immigrants and the occasional outbreaks of open violence. Finally, Chapter VIII traces the development of theories of population and of the naturalization controversy through the 1750s, when the idea of encouraging immigration to increase England's population and trade finally disappeared, and the naturalization debate came to an end.