Definition of Organizational PsychologyPsychology refers to the scientific study of human behavior and mental processes. It is about how individuals think and how the mind works. Therefore, it is reflected in the person's behavior. The objective of this unit is to review organizational psychology based on previous literatures and discuss the areas it covers in organizational psychology. Furthermore, this unit also describes the history of organizational psychology. The focus is not just on individuals; It also examines several aspects of the work environment, including the selection of the right people for a particular job, the influence of attitude on job performance, and how people work in groups (Ostroff & Judge, 2007; Thompson & Choi, 2006). according to Jex and Britt (2008), organizational psychology is one of the branches of the concept of industrial/organizational psychology which is the scientific study of individual's behavior in an organization, social processes and organizational effectiveness Meanwhile, Zaccaro and Klimoski (2002) stated that “organizational psychology tends to focus on interpersonal processes between individuals, nominally leaders and followers. Studies that explicitly examine leadership within organizational contexts, particularly from the strategic management literature, appear incomplete for other reasons. They typically ignore the cognitive, interpersonal, and social richness of this phenomenon, as they fail to address the processes that would explain the results. Furthermore, based on Silverthorne (2005), this field deals with human interaction on various aspects of psychological principles in the workplace and as in...... middle of paper ......action, productivity, motivation, health and well-being. The second objective is to change, improve and develop the quality structure of the organization through aspects such as the cognitive and behavioral state of workers, group dynamics, leadership, internal environment and work stress. Therefore, the external environment of the organization is capable of influencing the behavior and attitudes of employees in the work context. Meanwhile, employees also have a high tendency to transform the organization in a better way. Despite the emergence of systematic study in individual, group and organizational terms during the First World War, Prophet Muhammad (peace be upon him) had started using it during the Middle Ages when he successfully organized and led most of people on the right path of Allah. . He brought peace and prosperity to the Middle East and all Muslim-ruled lands.