Book excerpt: This book aims at explaining the variance in legal status, working conditions, social protection and collective representation of self-employed professionals across Europe. Despite considerable diversity, the authors observe three strategic models of mobilisation: the provision of services; advocacy, lobbying and the political role; and the extension of collective bargaining. They highlight the new urgent challenges that have emerged including the implementation of universal social protection schemes, active labour market policies likely to support sustainable self-employment, and the renewal of social dialogue through bottom-up organisations to extend the collective representation of project-based professionals.