The focus of Chapter 9 is the development of phonological skills, syntax and morphology in the preschool aged child. Great changes occur in the child’s ability to speak in multiple word utterances and use a variety of sentence types such as negation and question forms. This chapter describes the Brown’s Stages and use of mean length of utterance in morphemes (MLU) as a tool to measure development of grammar. In addition this chapter discusses the development of conjoining and embedding as more advanced language develops.