Twin children's language development

Scientific studies have consistently reported that, in group analyses, twin children have higher rates of language delay when compared with single-born children. This paper reviews the evidence on twin language by addressing five key questions: What is the extent of language delay in twin children? What are the causes of language delay in twin children? Do twin children have a separate, private or “secret language” which inhibits normal development? How might twin children's language development be supported and promoted? What are the future directions for research in the language development of twin children?