In this article, I discuss the acquisition of functional morphemes during the first years of life. Infants begin to process functional items at birth. They start encoding functional elements and their structural relations in phrases and sentences long before they can produce these items. Functional items also assist various language acquisition tasks. These findings demonstrate the initial acquisition of functional morphemes and early grammatical knowledge, challenging the view that no syntactic structures are represented before the end of the toddler years. The findings have important implications for theories of language acquisition and for the debate concerning nature versus nurture in development.