A recent development in the immigration policies of several European states is to make the admission of foreign nationals dependent upon criteria relating to their integration. As the practice of 'integration testing abroad' becomes more widespread, this book clarifies the legal implications which have hitherto remained poorly understood and studied. The book begins by looking at the situation in the Netherlands, which was the first EU Member State to introduce integration requirements. It explores the historical and political origins of the Dutch Integration Abroad Act and explains how, in this national context, integration has become a criterion for the selection of immigrants. It then examines how integration requirements must be evaluated from the point of view of European and international law, including human rights treaties, EU migration directives and association agreements, and the law on non-discrimination. The book identifies the legal standards set by these instruments with regard to integration testing abroad, and it draws conclusions as to the lawfulness of the Dutch approach. It is a compelling analysis of the state of international integration law that will be of interest to scholars and practitioners alike. (Series: Studies in International Law - Vol. 44)