In recent years, organizational citizenship behavior and deviant workplace behavior that is considered as non-task behavior and voluntary conscious behavior of employees has attracted the attention of many researchers. The increasing effects of non-task behaviors on the organizational and individual performance caused many researchers to search for their predictions. One of the factors affecting this type of behaviors is leadership. Leaders are on the most influential factors who affect the behaviors of the organization's members. Leaders can do many things to promote ethical practices in organizations.Therefore, this book will address the importance of ethical leadership on organizational citizenship behavior and deviant workplace behavior.