This chapter summarizes the major strains of psychology that were important in setting the foundation for death studies by psychologists, and highlights some of the most important contributions made by psychology to the field. Psychology, often regarded as an offshoot of philosophy and biology, traces its origin to Wilhelm Wundt who was what we today would call an experimental psychologist. A parallel track to that of experimental psychology is the development of the psychodynamic approach led by Sigmund Freud. A third school of 20th-century psychology is humanistic/existential psychology. It also focuses on the ability of the human being to mature and develop his or her own positive mental health. William Worden is the first clinical psychologist to differentiate between counseling and therapy early in the development of the field of thanatology. Psychology is made up of developmental, experimental, social, clinical, counseling, cognitive, and many other areas that defy simple classifications.