There is no single answer to the unity–multiplicity problem regarding the self for the simple reason that the term “self” is used by too many different theorists in too many different ways. In fact, there are several important substantive topic areas that need to be distinguished and studied scientifically. The topic areas I examine in this article are reflexivity, unit coherence, agency, and subjectivity. Each of these areas will be evaluated in terms of what it contributes to, and can be interpreted in terms of, the unity–multiplicity issue. It is proposed that we need a more differentiated technical vocabulary if we are to better understand the phenomena we are examining. Matching our technical vocabulary to this empirical detail sharpens the questions being asked and places the empirical facts in better focus. A more elaborate framework of conceptual differentiation provides a better basis for developing an integrated theory.