This paper compares the concept pair indexing/flagging with the well-known concept pair head/dependent marking that is widely used in typology. It shows that a general concept of flagging (comprising case and adpositional marking) is needed, and it sketches the advantages of the indexing concept over the older idea of “person agreement”. It then points out that the notions of head and dependent are hard to define (apart from the two basic domains of clauses and nominals), and that the head/dependent marking typology does not take the function of syntactic relation markers into account. On a functional view, both flags and indexes can be seen as role-identifiers, as opposed to concordants (attributive agreement markers). After discussing three further issues with the head/dependent marking typology, involving construct markers, concordants, and cross-indexes, I conclude that the concept pair indexing/flagging is more suitable for typological purposes than head/dependent marking.