This book is a unique and accessible reference guide to the work of eighty key figures who have played an important role in the development of ideas about language from antiquity to the twenty-first century. The entries are extensively cross referenced, allowing readers to trace influences, developments, and debates both in contemporary thinking and across time. Each entry concludes with suggestions for further reading of primary texts and secondary sources, encouraging readers to find out more about the particular key thinker and the impact of his or her ideas.