This essay seeks to apply the conclusions of the preceding discussion of the meaning of the structural principle to structure formation and structural change in analysis. Distinction is drawn between actual functional changes, that is, changes in the organization, patterning, and integration of psychic functions as matters of real self-modification, and changes attributed to higher order structural entities of the structural model, which have no real existence and consist entirely of theoretical constructions. Any agency attributed to these constructs is ascribed to them as substructures of the self exercising equivalently agency of the self in its relevant modality. These entities serve as convenient vehicles for us to think about, express, and categorize diversified actions of the self. What changes in both structure formation and therapeutic structural change are patterns of differentiation, organization, and integration of psychic functions. Changes attributed to id, ego, or superego are equivalently changes in how we think about and classify functional changes and their interrelationships.