The referential communication paradigm, which investigates the growth of the ability to send and receive verbal information, is described and the current state of knowledge reviewed. In particular, the explanations for communication failure are examined. Evidence from an international study is presented as an illustration of the difficulty that even older elementary school children have in detecting ambiguity in messages. It is argued that there is a case for the construction of a standardized test in this area, given its importance in educational achievement. The article concludes with a brief survey of work with language-impaired groups and approaches to intervention.