This study provides an overview of the policies and practices in 25 Member States and Norway with respect to third-country nationals in a prolonged situation of irregular stay. This includes both those who cannot be returned for legal or practical obstacles and those who remain unknown to the authorities. Services provided to long-term irregular migrants are limited, often discretionary, and even where available, difficult to access, while services available to undetected migrants with no authorisations are more limited still. the main service providers are national authorities and municipalities, with NGOs providing complementary and/or autonomous services. Across the EU Member States and Norway, (voluntary) return is considered the priority strategy to end longterm irregular stay, with four Member States choosing forced return.