Istvan Kecskes is a Distinguished Professor of the State University of New York, Albany. He is the president of the CASLAR Association and editor in chief of the CASLAR journal. Some of his books like Explorations in Chinese as a Second Language (Springer 2017) and Key Issues in Chinese as a Second Language (Routledge 2017) contributed significantly to research in Chinese as a Second Language.Hang Zhang is Associate Professor of Chinese Language & Linguistics at the George Washington University, Washington D.C. She has published monographs, journal articles and book chapters on second language phonology and Chinese pedagogy, including Second Language Acquisition of Mandarin Chinese Tones: Beyond First Language Transfer (Brill, 2018).