The aim of the study is to provide a thorough mapping of practices relating to the regularization of third county national illegally resident in EU 27 member states, with comparative reflections on regularization practices elsewhere. In addition, the study investigates the relationship pf regularization practices to overall migration policy framework, including the diverse interlinkages between regularization policies, protection issues and refugee policies and also the role of regularization regarding the framework for legal migration. Moreover, the study examines potential options for policies on regularization on European level, incorporating Member States as well as other stakeholders§ view on possible instruments on the European level. The study was published by ICMPD.