The Routledge Handbook of Digital Language Assessment

"Ten years after the Duolingo English Test began reshaping access to English proficiency testing, this handbook captures both the ambition and the evidence behind that work. It shows how digital assessment can be rigorous, fair, scalable, and deeply human."

– Luis von Ahn, Co-Founder and CEO at Duolingo

"A rigorous and timely contribution to digital assessment science. This handbook tackles AI-driven language testing where it matters: validity, fairness, security, and access. Grounded in evidence from the Duolingo English Test, it sets a new benchmark for responsible, scalable assessment design."

– Virginia Dignum, Professor of Responsible AI, Umeå University; author of The AI Paradox (Princeton University Press, 2026)

"A truly landmark volume surrounding the landmark for large-scale language testing that is the DET. Simultaneously reflective, innovative, and forward-looking, the contributions to this book—individually and in their aggregate—represent a singular moment, a powerful once-in-a-generation convergence of theory, practice, and technology in the universe of language assessment."

- Luke Plonsky, Professor of Applied Linguistics at Northern Arizona University

"This volume offers a thoughtful account of how contemporary testing systems are adapting to technological change and new modes of delivery. Bringing together a range of scholarly contributions, it makes a valuable addition to ongoing discussions of digital language testing."

- Micheline Chalhoub-Deville, Professor at the University of North Carolina at Greensboro

"Whether a budding researcher or a seasoned expert, The Routledge Handbook of Digital Language Assessment offers a wealth of insight into cutting-edge digital language assessment from the vanguard at Duolingo. Readers interested in everything from construct theory through technology, management, and stakeholder communication are sure to find this a unique and valuable resource."

- Aaron Olaf Batty, Professor at Keio University

"The Duolingo English Test continues to occupy a unique place at the vanguard of formal proficiency and certification examinations. This handbook provides high-level documentation of the internal DET ecosystem and the expertise required to build and support an agile, accessible, valid and trusted high-stakes proficiency exam."

- Brian Junker, Professor Emeritus, Carnegie Mellon University

"This landmark scholarly contribution brings theory and evidence together in a single, sustained argument about digital-first, AI-driven language assessment. Spanning theory, item generation, scoring, security, and impact, the handbook treats access, fairness, and responsible AI as validity questions rather than afterthoughts. A must-read for anyone rethinking language assessment today."

- Angel Arias, Associate Professor, Carleton University

"This absorbing volume is an absolute must for anyone seeking the knowledge necessary to navigate a period of significant transformation in language assessment. The essays collected here form a comprehensive body of research supporting the use of digital assessments, and will be invaluable to students, researchers, policymakers, and admissions professionals."

- Michael Goodine, Owner and Author at Test Resources in South Korea