Frege's extensional approach to reference affected his understanding of ontology in two ways: 1) it minimized the importance of his distinction between the complete being of objects and the incomplete being of concepts, and 2) it obscured the role of senses as "modes of presentation," by making it impossible to regard concepts as senses. Let us first situate the analytic interpretation of ontology within its historical context, next review Frege's comments on the being of concepts and objects more in detail, then discuss the levelling effect of his extensional approach to reference, and finally consider how that approach encouraged reductive interpretations of the meaning of "being'.