Analysis of Processes Leading to Changes in a Company Operating in the Aeronautical Sector: Towards an Evaluation Model for Ergonomic Interventions Although organizational changes are generally considered as generating longer lasting effects than those generated by individual changes, they are more difficult to implement. The literature on organizational change suggests that the participation of key actors at different hierarchical levels within the workplace can help identify changes that will be more easily accepted. Ergonomics is a discipline in which the participation of various actors has, for many years, represented a methodological necessity in order to make required changes when work organization is poor. However, there is a lack of knowledge related to the processes or actions done by the ergonomist that lead to the implementation of changes. The objective of this case study, conducted in an aeronautical company, is to accurately describe the actions of the ergonomist and to make recommendations as to which indicators to include in a process evaluation model for ergonomic interventions. In terms of results, a quantitative analysis of processes reveals how an ergonomist’s strategy can change at different stages of the intervention, based on certain key contextual elements. Qualitatively, this study shows how the stages prior to implementing changes are crucial in fostering the collective engagement of key actors involved in the action plan describing the changes to be implemented. This study makes a scientific contribution that relates to the evaluation of complex interventions, particularly the development of an evaluation model for ergonomic interventions. The results confirm the interest of conducting quantitative and qualitative analyses of processes and the importance of documenting the key contextual elements that influenced the processes and effects. That, from both the perspective of the facilitator and key actors. These findings could also apply to other types of organizational interventions. To continue this line of research, the evaluation of a series of ergonomic interventions would allow to deepen these results.