The document discusses three change management theories: the ADKAR model, the six change approach, and business process reengineering. The ADKAR model focuses on the five building blocks individuals require for successful change: awareness, desire, knowledge, ability, and reinforcement. The six change approach developed by Kotter and Schlesinger outlines six methods for preventing or minimizing employee resistance to change. Business process reengineering is focused on redesigning processes to dramatically improve performance metrics like cost, quality, and speed through seven principles like organizing around outcomes rather than tasks.