The main question considered in this book is: "Should a state promote immigration?" In the first chapter I assess the utilitarian arguments on immigration and weigh the objections related to them. In the second chapter, I discuss the liberal egalitarian arguments concerning immigration, the difficulties met in promoting the symmetry between the right of exit and right of entry. Issues discussed in this chapter include freedom of movement, asymmetry between exit and entry and the cosmopolitan account of open borders. In the third chapter I present the libertarian position on immigration, reveal the gaps in the argumentation and the inconsistency of promoting closed borders within this framework. The main problems reveal a discussion on self-ownership and freedom maximization, the conflict between the collective consent and the individual's decision in the case of immigration. The final conclusion argues that the moral principles presented so far for each framework can make us sustain open borders and promote immigration, even in the real world situations where immigration may have some negative effects.