To acquire competence with a natural language, young children must master the grammatical constructions of their language(s). In this chapter we outline the main theoretical issues in the field and trace the developmental path children follow from talking in single unit ‘holophrases’ to using complex, abstract constructions. We describe the development of children's initial skills with word order, case marking, and morphology as abstract elements in early constructions, and we discuss the level of abstraction characteristic of young children's grammatical constructions at different stages of development and in some different languages of the world. Finally, we consider the learning processes that enable young children both to acquire and to abstract across grammatical constructions.