This book offers a multidimensional analysis of task engagement in second language (L2) teaching and learning, with a particular focus on task-based language teaching (TBLT). It revisits key task-based theories and critically reviews the literature through the lens of task engagement, before presenting empirical findings on the factors that shape learners' engagement during task performance. The book offers theoretical and methodological insights into researching task engagement and links these insights to pedagogical implications for task design and implementation, as well as suggestions for teacher training and professional development. Bridging theory, research, and practice, this book helps researchers, language teaching practitioners, and postgraduate students develop a nuanced understanding of the nature and dynamics of task engagement in TBLT. It also provides practical guidance on how to design and implement L2 tasks that effectively engage learners in both face-to-face and virtual learning environments.