Ego-psychology
Ego-psychology (Fr. psychologie du moi) has been -- since its development in the 1930s -- the dominant school of psychoanalysis in the International Psycho-Analytical Association (IPA).
Sigmund Freud
Structural Model
It draws mainly on Freud's structural model of the psyche, which was first put forward in The Ego and the Id (1923).
This model comprises three agencies: the id, the ego, and the superego.
Since the ego plays a crucial role in mediating between the conflicting demands of the instinctual id, the moralistic superego and external reality, more attention began to be paid to its development and structure.