Nominals that undergo (pseudo) noun incorporation ((P)NI) need not, and in many cases cannot, enter into case/agreement relationships (e.g. Baker 1988, 1996; Massam 2001). Baker contends that this complementarity arises, because NI has the same effect on nominals as case/agreement. Both processes render the nominal `visible’ (in the sense of Aoun 1980, Chomsky 1981) for thematic interpretation. Such an account can be straightforwardly extended to PNI if PNI involves covert head movement (Baker 2014; pace Massam 2001). However, a growing body of research has argued that noun phrases need not receive C/case, be agreed with, or undergo (P)NI to be licensed and interpreted. These conclusions force us to reconsider the apparent complementarity of Case/Agreement and (P)NI. In this talk, I argue that the two phenomena are nonetheless complementary, but for a different reason. Nominals, like all extended projections, are subject to a general requirement that they be complete. For instance free-standing clauses must be CPs, and free-standing nominals must be KPs. It is this completeness requirement on extended projections that underlies the observed complementarity of case/agreement and (P)NI. When a noun phrase is complete, i.e. a KP, it will be eligible for case/agreement. If a noun phrase is structurally reduced, i.e. smaller than a KP, it must undergo head-movement into another extended projection which itself will become/is complete.