This document discusses the essential roles of assessment, measurement, and evaluation in task-based language teaching. It begins by outlining some of the key issues and debates around TBLT, including whether it is effective and for whom. It then discusses the need for empirical measurement and assessment that is aligned with educational purposes to better understand how TBLT works and how to enable task-based learning. Problems of practice are identified, such as lack of construct definition and standardization. The role of evaluation in articulating empirical practice to improve TBLT is also discussed.