This book charts the development of mobility and welfare rights for those citizens exercising their right to move or return home on retirement under the Free Movement of Persons provisions and explores their experiences of international mobility. It is set within the context of 'Citizenship of the Union'. Senior citizenship? draws on substantial primary research material to: combine detailed analysis of the framework of EU rights shaping social with in-depth qualitative interviews involving retired migrants across six member states (Greece, Portugal, Italy, the United Kingdom, Sweden and Ireland); describe and evaluate an innovative approach to comparative enquiry that combines biographical interviews with legal and qualitative analysis; highlight the diverse nature of retirement migration encompassing the experiences of returning workers, migrating retirees and post retirement returnees. Topics are explored thematically in the context of comparative social policy, raising important and topical issues around the future of social citizenship and the implications of the exercise of agency, in an increasingly global and mobile world.