Cognitive Task Complexity and Second Language Performance provides an overview of research focusing on the effects of cognitive task complexity (CTC) on second language (L2) performance. The edited volume brings together renowned scholars in the field who present data-driven insights into the intricate relationships between CTC and L2 performance, drawing on a combination of empirical studies and theoretical analyses. Each section summarizes the intersection of task complexity frameworks and models of second language production; synthesizes critical issues and research findings; and moves beyond the routine discussion of task complexity features and models of speaking, extending the discussion to the interface of task complexity features and (a) learner engagement, (b) virtual interaction, and (c) corpus linguistics. It also delves into the interface of CTC and technology, exploring how digital tools and resources can enhance task complexity and ultimately impact L2 performance. Overall, this edited volume not only consolidates the existing research on CTC and L2 performance but also highlights areas that require further investigation. In charting a course for future research and pedagogy, the book is a valuable resource for students, scholars, researchers, and practitioners seeking to deepen their understanding of CTC and its impact on second language acquisition.