By focusing on the issue of vulnerability and humanitarian considerations, scholarship on recent migration flows has underestimated the role of work as a source of legitimacy and access to rights. Yet, while officially employment is a means of obtaining a residence permit for only a minority of migrants, it remains a determining factor in the existence of migrants with precarious legal status. Based on the French case, this article describes the different ways in which the moral economy of employment structures the successive moments of migratory irregularity. It examines the effects of administrative precarity on a range of employment relationships, the documentation strategies that make them possible and the moral arrangements that result between undocumented workers and their employers. It then highlights the different forms of employment and the various actors involved in the dynamics of obtaining legal status. Finally, it examines the effects of regularisation, identifying the biographical changes it brings about while revealing the lasting effects of past irregularity. The conclusion reintroduces the issue of economic performance in the critical analysis of humanitarianism by reminding us that the latter is also permeated by neoliberal considerations, valuing promising victims. By underlining the role of work within the moral economy of the migration-citizenship nexus, the article exposes the ambiguities of the injunction to economic performance in the construction of migratory legitimacy.