The chapter presents a blockmodeling analysis of multilevel (inter-individual and inter-organizational) networks. Several approaches are presented and used to blockmodel such networks. Each blockmodel represents a system of roles (White et al., 1976) and therefore a form of division of work that is likely to change over time in fields of organized collective action. Using a case study, we show that while the systems of roles are quite similar at both levels (core-periphery-like structures with bridging cores interpreted in terms of division of work between actors’ and organizations’ specialties, location, status, etc.), the roles are performed by units with different characteristics at different levels. The added value of this true multilevel analysis is to show how groups at different levels are connected. In the empirical case analyzed in the chapter, the division of work at the level of individuals and the division of work at the level of laboratories can complement and strengthen each other for some segments of the population, while this reinforcement does not work for other segments. For the same roles, the mix of specialties at one level is different from the mix of specialties at the other level, notably because the two levels do not manage the same resources. Thus, this analysis tracks the meeting of top-down and bottom-up pressures towards structural alignment between levels.