Structural change is usually defined in terms of impulse-defense configurations and modifications in the relations among ego, superego, and id. I am proposing, instead, based on findings regarding the psychopathology of borderline conditions, that impulse and defense should be explored in connection with patterns of internalized object relations, which I see as the "building-blocks" of the tripartite structure. Patterns of object relations, character, and transference developments all reflect the nature of these building-blocks.