W ho are you? This is a question that has been posed by people rangingfrom The Who (1978) to Inigo Montoya of Westley during their classicleft-handed duel in The Princess Bride (Goldman, 1987) to infuriated parents and lovers throughout the ages. When used in a colloquial sense, we expect the respondent to reply with a name, an occupation or a relevant social role, and with some personality traits or other self-relevant attributes. Presumably, the response requires consulting one’s self-concept content for the answer. Although the self-concept is filled with such content, we suggest that to fully appreciate the value of knowing this content, we must also consider self-concept structure as well. This is the overarching theme of our chapter.