This project investigates when and how children identify the basic ‘clause types’ of their language and the ‘speech acts’ that they are typically associated with. While languages across the world tend to distinguish the same clause types (declaratives, interrogatives and imperatives) for the same speech acts (assertions, questions, requests), the form that these clauses take varies greatly from language to language. This project asks when children first differentiate questions from assertions, when they associate these acts with specific clause types, and how the acquisition path differs as a function of language-specific features of clause types, through a comparison of acquisition across languages. We hypothesize that the mapping between clause type and speech act is a crucial precursor to the acquisition of syntactic features that emerge before age two, and that infants figure out form and function in tandem, in mutually constraining the other. We test these hypotheses through experiments documenting the development of this mapping between 1- and 2-years of age, and through corpus analyses, and computational modeling.