Changes to the organization of work (e.g. “lean production”), which currently appear to be spreading across work environments, are strongly suspected to be responsible for reducing worker empowerment and job control, indirectly threatening health and safety. This exploratory ergonomics study aims to better understand the conditions for workers’ room for maneuver, as a key for preventing musculoskeletal disorders (MSD), stress, and psychosocial risks. After providing some definitions of the concept, a case study from a lean automotive supplier plant is presented. At the time, a “one-piece-flow” organization of production was being implemented in seven new production cells, raising concerns about potential negative health outcomes (MSD). The ergonomics intervention took place immediately after the first stages of this organizational change project, allowing comparison of three coexisting configurations. The intervention analysis was based on interviews and observations of workers’ activity in order to identify the room for maneuver and potential negative outcomes.Focusing on the assembly tasks performed inside each of the “one-piece-flow” assembly cells, the results showed rigid work organization, a densification of the activity and strong interdependencies between workers, leading to a loss of room for maneuver and interpersonal conflicts. However, a wider view of the work situation, including those parts of the workers’ time spent outside the cell, interacting with managers and engineers (preparing, reporting, etc.), yielded more ambivalent results. For instance, nightshift workers created an alternative to the standard operating procedure in order to make their work conditions more bearable. However, their perceived overall workload was higher than for the other teams. The management were aware of the new procedure, known amongst workers as the “pendulum way”, and as quality and productivity results were excellent, the procedure was tolerated conditionally as an experiment. This example invites ergonomists to distinguish between given and taken types of room for maneuver and to pay attention to the relationships between them. Further methodological developments are needed to better characterize room for maneuver (conditions, origins, and limits) and to more fully understand its dynamics during the implementation process.