This volume has been written specifically with TESOL teacher educators, practitioners, and classrooms in mind. It is divided into three sections: cognitive aspects of language learning, individual differences, and language learning difficulties and challenging behaviours. Structured in this way, it enables TESOL teacher educators and practitioners to better understand how language learners process and retain new information, improving their overall ability to learn and remember. In addition to supporting TESOL teacher educators and practitioners in promoting effective language learning, this volume explains individual differences among language learners and the importance of developing learners’ emotional, social, and behavioural skills while addressing learning difficulties, disorders, disabilities, and challenging behaviours whenever required. The individual chapters are written in an accessible style to enable readers to explore various psychological concepts in their pedagogical practice by engaging in reflective teaching through action research. This volume is a vital resource for pre- and in-service language teachers and will encourage language teacher educators to reassess their existing practices. Chapter 2 is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.