Western societies have witnessed the emergence of a new economic model in which companies take the form of digital platforms and act as intermediaries between clients and service providers as well as between job seekers and job suppliers. The distinctiveness of this model lies in the fact that the latter are not employees but independent workers. Yet throughout the world and also in Europe, platform workers have taken legal action to have their labor status upgraded to salaried work. What exactly does this category of platform workers cover? Are platform workers ultimately either self-employed or salaried workers, or is there a new category in the making? Will we one day find an appropriate legal term for these workers? These seemingly simple questions of categorization are in fact rather complex. This chapter combines sociological and legal perspectives to describe and analyze the processes by which the work of categorization is carried out in law and sociology, to identify the ways in which sociological categories are transcribed into legal categories, and to underscore the crucial role of the law in constructing these social categories. In so doing, we focus on the emblematic case of Uber drivers in France and other European countries.