This article reports the results of research carried out in London using five-year-old children of working class and middle class backgrounds. Speech samples were collected and compared on the basis of grammatical categories. It was discovered that working class children used more pronouns than their middle class counterparts in third person nominal groups. The middle class children's greater use of nouns was considered significant because nouns, in contrast to pronouns, can be expanded by modifiers and qualifiers and because their reference is more specific and does not make so many demands on the listener or assume any knowledge on his part. The author relates these findings to Basil Bernstein's concept of restricted and elaborated codes, demonstrating that working class children's speech has the characteristics of a restricted code (one used among small closely knit groups, where implicit knowledge of the speaker's intention is important for understanding), whereas middle class speech has the characteristics of an elaborated code, in which the speaker's intentions are made more explicit verbally without much reliance on other means of communication. The author believes that the working class child's reliance on a restricted code, traceable to his family and cultural environment, accounts for his verbal difficulties in school. (FWB)