In the 21st century, there is a great need to rigorously examine "old" issues through newer perspectives and to put forth contemporary ones for thorough and proper consideration. With the widespread use of English in diverse contexts, the accumulation of knowledge and the innovations in all fields of study as well as the changes in every step of life around the world, things got more complicated and, at times, it has become harder for English language scholars and practitioners to find their ways. The book is an attempt to address the affordances and caveats regarding TESOL-related issues in the 21st century. The aim of the volume is to provide a comprehensive picture of the TESOL-focused research on an international level by shedding light onto the status of TESOL in the 21st century with the challenges and opportunities. The volume is intended to address the state-of-the-art TESOL-related issues for prospective and in-service teachers, language teacher educators, course developers and researchers.