Professor Sun studies Chinese linguistics, morphosyntactic changes in the history of Chinese, sociolinguistics, and Chinese syntax. His books include, Chinese: A Linguistic Introduction. Cambridge, England: Cambridge University Press, 2006 and Studies on Chinese Historical Syntax and Morphology Co-editor. Ecole des Hautes Etudes en Sciences Sociales, Center de Recherces linguistiques sur l'Asie Orientale, Paris, 1999. He teaches Classicial Chinese, Structure of Chinese and Seminar on Chinese morphosyntactic changes. He has been president of the Chinese Language Teachers' Association of California and is the Director, Board of Directors, Inter-University Program for Chinese Language Studies, Berkeley, 2002-present.