Increasing immigration numbers in many parts of the world make it crucial for policy makers to think about effective integration policies. In this volume of the CESifo Forum we shed light on important mechanisms of immigrant integration: Access to citizenship and legal status in the destination country. Today's citizenship laws are historically shaped by the legal traditions of each country. Birthright citizenship, as one of those traditions, early access to citizenship and legal status in a country play a major role in the context of successful integration strategies. Our contributors show that liberalizing citizenship laws and easing legalization foster the educational, economic and social integration of immigrants. Gender-specific effects can be observed and should be considered in policy measures.