Definition extracted with permission from Simon, Fritz, et al, Family Process, Inc.:[amazon 0961551909 inline]
Ego psychology concerns itself with the development, structuring, and functioning of the ego. Ego is a theoretical construct defined in terms of its function, which is to insure the survival of the individual by organizing, integrating, and adapting (adaptability) internal/external perceptions and demands to the environment. One's capacity for self-organization is determined to a great extent by one's interaction with his or her familial environment. Thus, there is a correlation, if not direct correspondence, between the theories of ego psychology and theories of family therapy; in both a developmental perspective is implied and the principles of coevolution can be applied.