This twin-volume collection showcases unique explorations into the future development potential of English Language Teaching (ELT) research, encompassing traditional boundaries of the field and pushing beyond them. This first volume offers an in-depth examination of current issues and future prospects from diverse perspectives within the ELT landscape. Authors address key research topics, including English for Specific Purposes (ESP); English for Academic Purposes (EAP); vocabulary, grammar, and skills instruction; teaching young learners; the utilization of information and communication technology (ICT) and generative artificial intelligence (AI), as well as classroom research and teacher education. The first volume provides a comprehensive view of ELT research by exploring the symbiotic relationship between theory-informed practice and practice-informed theory. Traditionally, these various areas of ELT have been discussed independently. However, this volume organizes these research issues based on the five W’s and one H (i.e., who, what, where, when, why, and how), showcasing how research outcomes can be seamlessly integrated into ELT practices. With this approach, readers will not only gain insights into the latest research findings in ELT, but also learn how to practically apply them in teaching and learning contexts.