This book has been developed from a research about Problem Solving and Legitimacy in the context of cultural diversity. It has done in Iranian state and non-state institutions. The main idea of this book is explanation of Problem Solving and Legitimacy according to cultural diversity context in Iran. It is intended for University courses that educate culture and work in Problem Solving areas, also we find this book useful for companies Legitimacy in cultural diversity context. In other hands, this book seeks to determine the key collective, social criteria's that legitimize organizations. Our goal is to create a comprehensive account of how various types of organizations acquire their legitimacy from different constituencies and stakeholders in the external environment.