The origins of Grammar present a synthesis of work done by the authors, using one of the most important methodological, advances in language learning in the past decade: the intermodal preferential looking paradigm, which can be used to assess lexical and syntactic knowledge in children as young as thirteen month of age. The origins of Grammar provides a new way of thinking about the process of language comprehension. The Analysis borrows insights from theories about the development of mental models, models of early cognitive development, and systems theory and is presented in a way that will be accessible to cognitive and developmental psychologist. The chapters include: theories of Language acquisition; The Intermodal Preferential looking Paradigm; infant’ Perception of Constituent Structure; Single Word speaker’s Comprehension of Word Order; Young Children’s use of Syntactic Frames to Derive meaning; and A coalition Model of Language Comprehension.