This book has two goals, each related to the validity of language assessment. The first goal is to explore the difference between fairness and justice in language assessment. The authors distinguish internal and external dimensions of the equitable and just treatment of individuals taking language tests which are used as gatekeeping devices to determine access to education and employment, immigrant status, citizenship, and other rights. The second goal is to show how the extent of test fairness can be demonstrated and improved using the tools of psychometrics, in particular the models collectively known as Rasch measurement. “This book will have an enormous impact on the field of language assessment. Using Rasch analysis models to explore and identify sources of unfairness, the authors make a compelling case for fairness in the design and implementation of language assessment instruments and for justice in the interpretation and use of test results. A real strength of the book is that it guides readers through analytical techniques in an accessible way.” Dan Douglas, Professor Emeritus, Applied Linguistics Program, Iowa State University.