This chapter reviews the phenomenon "acceptance" in a multitude of dimensions, placing it opposite avoidance and resistance, and analyzing it as an active rather than a passive process. Acceptance is reviewed as a conscious act, a management tool, an internal purifier, a satisfaction strategy, a therapy and a foundation for action. The chapter reviews acceptance as a means of understanding the big picture, granting or acquiring a sense of belonging, balancing or leveling ambition, safeguarding personal well-being and improving future performance, obtaining peace of mind, coping with changes and taking charge. It shows multiple dimensions to be distinguished when considering employees' acceptance of change, such as openly expressive support, concealed support, active support, and passive support. The Acceptance and Commitment Therapy (ACT) has significantly contributed to positive outcomes in substance abuse, high-risk sexual behaviors, exhibitionism, post-traumatic stress disorder, self-harm and smoking.