The Development of Grammar in Spanish and the Romance Languages applies Mayerthaler and Bailey's seminal work in linguistic naturalness and markedness to child language development. The focus is on Spanish in its many varieties, including its 'daughter' creole, fusion and koine languages, but Faingold also draws on evidence from Portuguese, Italian, Rumanian and French in the course of systematically examining the acquisition of a range of grammatical constructions. The account is further enhanced by reference to historical language change, contact language phenomena, creolization and second-language learning. This highly integrated new study demonstrates a new impetus and predictive force for markedness theory.