Research interests: Language Acquisition, Applied Linguistics, Sociocultural Theory and Second Language Development. 

The Greer Professor in Language Acquisition and Applied Linguistics in the Department of Applied Linguistics at the Pennsylvania State University. He is Director of the Center for Language Acquisition, and Director of CALPER (Center for Advanced Language Proficiency Education and Research). He was president of the American Association for Applied Linguistics (2005), co-editor of Applied Linguistics (1993-1998), and is founding editor of Language and Sociocultural Theory. He has published over 100 journal articles and book chapters and is co-author of Sociocultural Theory and the Genesis of Second Language Development (2006, Oxford University Press). His 2014 co-authored book, Sociocultural Theory and the Pedagogical Imperative: Vygotskian Praxis and the L2 Research/Practice Divide (Routledge) received the Mildenberger Prize of the Modern Language Association of America for its contribution to the teaching of language and culture. He has published several edited and co-edited volumes, including Vygotskian Approaches to Second Language Research (1994), Sociocultural Theory and Second Language Learning (2000), and Sociocultural Theory and the Teaching of Second Languages (2008). His new co-edited volume The Routledge Handbook of Sociocultural Theory and Second Language Learning will appear in June 2018. In 2016 he was named Changjiang Professor in Applied Linguistics at Xi’an JiaoTong University; he also received the Distinguished Scholarship and Service Award of the American Associate for Applied Linguistics. In 2017, the School of Foreign Studies at Xi’an JiaoTong University established the Lantolf Research Center for Second Language Studies in his honor.