The main aim of this research is to analyze the relationship existing between the management of tacit knowledge and the management of change processes in organizations. For this purpose, a case study has been undertaken in three public organizations in Uruguay where radical change processes were carried out. The main findings of the research to be highlighted are as follows: first, the way the change process is managed has an impact on organizational tacit knowledge, mainly involving a transformation of collective mental models. Second, tacit knowledge management has a positive influence on the change process, especially through the development of new competences based on the experience of people who facilitate consolidation of the change. On the other hand, tacit knowledge management also has a negative impact on the change process. In particular, tacit knowledge arises as a source of resistance to change, basically due to some people overvaluing their experience, making them reluctant to change their working routines. Finally, management of the change process also has a negative impact on organizational tacit knowledge. Indeed, as a consequence of the change process, a significant amount of tacit knowledge has been lost due to people leaving the organization. This research has relevant practical implications for managers. In particular, it could help managers to better manage organizational tacit knowledge in order to facilitate the implementation of change processes. Moreover, it may be useful for improving the way change processes are managed and implemented.