This article investigates emergence, development and existence of the science branch known as Educational Psychology. The topic has been studied on the basis of a historical perspective from both national and international aspects. Educational Psychology is a field born via interaction between psychology and education. On emergence of the field, William James, Stanley Hall, John Dewey, Edward L. Thorndike played a significant role. Educational Psychology has been classified as a sub-branch of psychology with regard to thoughts of authorities mentioned. Studies in Turkey related to this field started with the course named Educational Psychology which was replaced after abolishment of Pedagogy courses taught at Teacher Training Institutions in 1952. During this process, Educational Psychology has been alienated to Educational Sciences into which it is positioned. At that point, it has become dysfunctional to contribute to education. With this regard, it is suggested that the field of Educational Psychology is to be positioned as a sub-branch of psychology.