Dr Trevor Johnston is Associate Professor of Sign Language (SL) Linguistics in the Department of Linguistics, Macquarie University, Sydney, Australia. He has researched and published on Auslan (Australian Sign Language) since the early 1980s concentrating on lexicography, grammatical description, bilingual deaf education, and corpus linguistics both for research into sociolinguistic variation and for empirical language description. He has authored several dictionaries of Auslan (in book, CD-ROM and internet formats). He has conducted research in the area Auslan assessment, especially as a first language, in the evaluation of sign bilingual education programs. In 2008 he completed the initial compilation of the Auslan corpus (funded by the Hans Rausing Endangered Languages Project, University of London). The annotation and analysis of this corpus is a long-term on-going project. He is Chief Investigator on two current projects: the first on Auslan/English interpreter-mediated communication in health and medical settings, focussing on developing, sharing and harmonizing the use of medical terminology in Auslan through Auslan Signbank (an internet-based dictionary of Auslan); and the second on comparing variation in Auslan and British Sign Language (a closely related sign language) for evidence of the hypothesis that grammar is emergent from language use and is driven by frequency and usage which is reflected in the processes of grammaticalization and language change.