The document discusses two models for understanding and managing organizational change: the Transition Model and the Change Curve. The Transition Model developed by William Bridges describes change as a 3 phase process: 1) Ending, which involves letting go of the past, 2) Neutral Zone, a transition period marked by uncertainty, and 3) New Beginning, when people commit to the change. The Change Curve model predicts that change will negatively impact performance until people accept the change and integrate it. Both models aim to help leaders guide individuals and organizations through the emotional aspects of change.