Undocumented migrants – including illegal”, overstayers, rejected applicants for asylum, non-registered EU-migrants, or formerly “regular” migrants – are typically marginal to the rights and service provision of receiving societies, although with strong variations across and within them. Their claims and needs are often addressed, if at all, by grassroots civil society initiative and through their informal ethnic networks, rather than via institutional welfare provision. Their very existence may be a source of major ethical and substantive dilemmas to welfare practitioners and their agencies, against a background of generally hostile public opinions.Our session, which is expected to form part of the IMISCOE 2015 conference in Geneva, AIMS to advance knowledge and the public debate on the position, entitlements and protection of undocumented migrants, vis-à-vis all sort of social and healthcare agencies or receiving societies.”