The primary purpose of this article is to examine the cognitive underpinnings of grammaticalization processes that generate quantifier noun constructions in Spanish. This analysis aims to demonstrate the need to develop a cognitive model of grammaticalization based on the Theory of Blending. Grammaticalization is thus considered a specific case of blending. The main argument sustaining this position lies in the emergent properties of the constructions that result from grammaticalization processes. Finally, a framework for such a model is outlined and its comparative advantages vis-à-vis other cognitive models of grammaticalization proffered in the literature are explained.