This review essay examines recent work in political theory on the ethics of immigration admissions. It considers arguments put forward by Michael Walzer, Peter Meilaender and David Miller, among others, for state control of borders. Such arguments tend to appeal to the value of political communities and/or the exclusion rights of democratic associations, and I argue that neither of these are successful. Turning to work by Joseph Carens, Phillip Cole, Michael Dummett and others who advocate open or much more open borders, the article considers various arguments that would support this stance, including appeals to freedom of movement, utilitarianism and social justice. I argue that rights to immigration need embedding in global principles of resource redistribution. In the conclusion I sketch a cosmopolitan approach to immigration by which impartial criteria such as population density and gross domestic product would determine how many migrants states have a duty to admit.