This book provides an accessible guide to concepts in language testing and the testing of specific skills and systems. It combines theory and practical recommendations to help teachers understand the principles of testing and how they can be applied, supporting them to write better tests. The third edition has been extensively revised and updated to reflect recent developments in the field, while retaining the straightforward approach that made the earlier editions essential reading for trainee and experienced teachers alike. It features new content on technology, including computer adaptive testing and the use of automated scoring for all skills. It also includes an extended discussion of language testers' responsibilities, new chapters on non-testing methods of assessment and a checklist to help teachers choose tests.