This book chapter of Léon de Caluwé and Hans Vermaak elaborate on complexity and multiplicity in change processes. Given that more organizational change takes place unplanned than planned, and more unsuccessful than successful, there is much reason to reflect on why change does not work. Léon and Hans discuss several perspectives on irrationalities and why change processes are so often frustrating events. They suggest that over-reliance on rational top-down and contingency approaches can be rendered fruitless as a result of these irrationalities. After reflecting on the question what makes change work, five prevailing paradigms about changing are explored. Each of these paradigms are associated with beliefs and assumptions, and characterized in terms of their characteristics such as predictability, ideals, pitfalls, action strategies, style of change agents, and intervention methods. The presentation of this multiplicity approach could help participants to deal with complexity in processes of changing. The ability of change agents to take a multi-paradigmatic perspective could help to gain insight in the lack of success of planned change. Taking a multi-paradigmatic perspective allows becoming aware of ways of defining and solving problems, and opens up new possibilities by making conscious and collective choices for organizing and changing.