AbstractStatistical profiling algorithms claiming to predict which jobseekers are at risk of becoming long‐term unemployed are spread unevenly across countries. However, the pathways and histories of these tools are understudied. Because the profiling path in France is a winding one, it is fruitful to study the production of profiling acceptability within the Public Employment Service (PES), and upstream of its reception by frontline advisers. Using a mix of interviews and written sources, we show that the production of profiling acceptability sits at the crossroads of two processes: technical and political transformations of the instrument itself and broader institutional and managerial transformations of the PES. On the basis of this case study, the paper enriches our understanding of the slow and incremental rationalization of public services that we have termed “professional rationalization.” We argue that, far from being a softened or moderated form of bureaucratic rationalization, it is powerful—perhaps even irreversible—precisely because it transforms its target (frontline advisers) before the rationalization instrument is even deployed.