Nowadays, companies are more and more confronted with changes that are external (competition, competitiveness, technological innovation, market fluctuations, legal changes, etc.) or internal (change of concept, implementation of new systems, change of direction, moving, etc.). These changes can destabilize and disrupt employees, which generates behavioral transformations such as blockage, fear, reluctance. The latter can generate resistance, or outright a rejection of change, hence the need to inform employees on the how and why of change? And support them in order to reduce these behaviors and encourage employee buy-in. In this article, we will try to identify the sources of resistance to change, to define the key steps to manage the resistance that employees may have to change management projects. And finally, we will explain how to drive organizational change within a small and medium-sized enterprise to achieve operational excellence.