Building on recent work on anaphoric definiteness, this paper presents arguments that there is a general distinction between plain and indexed definite DPs, distinguished by the presence of a syntactically rep- resented index—IdxP—in [Spec, DP]. Typical instances of indexed definites include anaphoric definites, complex demonstratives (e.g. that linguist), and pronominal definites (e.g. we linguists). Several arguments for in- dexed definites are brought together from the syntax and semantics of referential expressions in English and Mandarin and the typology of defi- niteness marking. A new argument for the proposed syntax and semantics is then presented from anaphoric definite DPs in Marka-Dafing (Mande). Co-occurrence restrictions between exophoric and anaphoric demonstra- tives in Marka-Dafing, which are argued to be quite general, provide addi- tional support for the idea that indexed definites use a dedicated syntactic position in [Spec, DP].