In this article, we want to examine the role played by precarious labor in the process of building up and consolidating rank and file unions in Argentina. We speculate about the interaction between precarious labor and union organization in the workplace; and about which elements allow this interaction. This analysis of the interaction (as opposed to the separation) of both processes emerges from our own empirical research, but also from the attempt to establish a theoretical prudence in the face of Social Science's tendency to create “new phenomena” and isolate them from their procedural frame. The academic logic paradigm of Segmentation (and its conformation of “case studies” in places where there are only fragmentary processes) forces us to look at precarious labor as a subject itself, dissociated from steady labor, thus separating it into different ways of organization and resistance. The re‐composition of rank and file trade unionism in Argentina shows gray areas in which the overlapping of precarious labor and steady labor in the same working area forced the interaction between the new and the old.