The initial defining framework of the primary process based on flow of psychic energy has been largely rejected by contemporary psychoanalytic theorists, but the concept remains in use clinically, particularly in application to the flow of associations and the interpretation of dreams. Some researchers have attempted to characterize primary process thought in terms of contents and formal properties of thought without reference to the energy framework, but this approach fails to account for the role of emotional intensity in mental life. The integration of affective arousal with particular properties of thought that is central to the primary process concept can be understood today in the context of current research in cognitive psychology, emotion theory, and neuroscience. The version of multiple code theory outlined here provides a framework for the involvement of affect in productive and complex mental operations in areas from sports and the arts to scientific discovery, as well as therapy, and also provides a basis for empirical research.