With the growing recognition of the need to broaden the definition of Interactional Competence (IC) for communication and learning, this monograph offers the first book-length treatment on the conceptualization, development and validation of IC assessment instruments. Combining psychometrics with discourse analysis, highlights of the book include: 1) evidence that a holistic IC construct – encompassing the sequential, emotional, logical, moral and categorial dimensions – can be assessed reliably, 2) a practical IC rubric that is adaptable to diverse languages and contexts, 3) demonstration that L2 speakers can have stronger IC than L1 speakers. The book argues that IC needs to be taught and assessed for both L1 and L2 speakers to promote fairness in language education. In this superb, meticulously designed, intellectually coherent book based on awardwinning scholarship, David Wei Dai takes the reader on a riveting journey tackling key challenges in assessing Interactional Competence. Ingenious and groundbreaking; there is no looking back. (Talia Isaacs, University College London) David Wei Dai’s book is an exemplary study of test development and validation. It breaks new ground in the assessment of Interactional Competence, and is an invaluable resource for novices and seasoned researchers alike. (Carsten Roever, University of Melbourne)