Psychology has its roots in mythology, religion and philosophy. People believe that the chronology of psychology goes as far back as the age of the sage Greeks. In particular, many believe that several hundred years B.C., it was Plato and Socrates that started the academic pursuit of understanding the human mind and behavior. But it was not until the 1870's that psychology had become ready to set itself as an independent academic field.

1873 - Wilhelm Wundt published "Principles of Physiological Psychology".

1874 - Franz Brentano published "Psychology from an Empirical Standpoint".

1879 - Wilhelm Wundt established the first formal psychological laboratory at the University of Leipzig in Germany where he introduced a scientific approach to psychology and performed many experiments to measure peoples' reaction time. This event is considered the birth of psychology.

- Also in 1879, on the mental health front, the first public mental hospital in what would become South Dakota was opened in Yankton.

1880 - Francis Galton published "Statistics of Mental Imagery", in which he introduced systematic use of questionnaires

1883 - The first psychology laboratory in America was established at Johns Hopkins University by G. Stanley Hall.

1888 - James McKeen Cattell, Wundt's former student, became America's first professor of psychology at the University of Pennsylvania.

1892 - Edward Titchener, Wundt's former student, introduced Structuralism in America.

- The American Psychological Association (APA) was founded in 1892.

1900 - Sigmund Freud presented his concepts of psychoanalysis in a publication entitled "The Interpretation of Dreams."

1906 - Ivan Pavlov published his findings regarding classical conditioning.

1908 - William McDougall published "An Introduction to Social Psychology" and established the field of Social Psychology.

1909 - Freud and Jung visit the United States. Sigmund Freud presented his concepts of psychoanalysis at Clark University.

1912 - Max Wertheimer introduced Gestalt psychology.

1913 - John Watson published "Psychology as the Behaviorist Views It", thus introduced "Behaviorism" which views psychology as a network of conditioned responses.

- Carl Jung departed from Freudian views and developed his own theories.

1953 - The American Association of Psychology published the first "Code of Ethics of Psychologists".

1954 - Abraham Maslow published "Motivation and Personality", introducing a hierarchical theory of human needs.

1957 - Noam Chomsky published "Syntactic Structures" which lead to the creation of a new field known as Psycholinguistics.