This paper examines research findings about language development and their implications for classroom teaching. It first discusses early analyses of child grammar, which led to descriptions of the telegraphic nature of the speech of very young children and to the classification of child grammar into pivot and open classes. It then points out limitations of the concept of pivot grammar noted by later researchers and describes recent investigations of child language that reveal a shift from pure syntactical descriptions to descriptions involving semantics. The paper then discusses many classroom-related aspects of language development. Among the topics it considers are the use of syntactic indexes to determine a child's level of language development; ways of helping children deal with language representing spatial and other complex concepts; the importance of creating a language rich classroom environment to enhance children's language development; and the role of the classroom in ensuring that children have the necessary interaction to add continually to their knowledge of word meanings. (GW)