At the heart of this collection is a process (international population movement) and a set of core dilemmas that underlie it, such as the impact of economic inequalities and conflict. The implication of the process and associated dilemmas actually stretch far beyond a narrow focus on people moving from one country to another. The basic issues in the study of international migration addressed by this collection are why people move from one state to another and how states and other actors respond to this movement. The answer to the first past of the question is relatively simple and by thinking about it we can begin to see the resonance of international migration in political science and international relations.