The postulation of the theory of aggression as an instinctual drive has been productive in illuminating vicissitudes of child development and behavior. Observations from psychoanalytic treatment, from nonpsychoanalytic settings and from experiences in applying psychoanalytic theory in the service of educating and caring for children can elaborate and refine the psychoanalytic theory of aggression. Such elaborations and refinements suggest trends in theory building in psychoanalysis and can lead to new hypotheses. At the same time, psychoanalytic theory can be useful in improving services for children.

The resonances that can be set up between theory building and expository views of a child's behavior are particularly enriching and vital for the elaboration of our science. This trend also