Bringing together theory and research within the field of L2 oral proficiency, with the concept of L2 encompassing any language learned later than the early childhood years, this book provides a state-of-the art overview of what is at stake for L2 learners and examiners, and advice on how to approach testing and assessment. Using data and findings from empirical research to illustrate and discuss key topics, takes the reader step-by-step through the major concepts and issues in the oral assessment of second languages, with a main focus on L2 English. Investigating and explaining the most important educational and interactional issues facing both examiners and test-takers, such as the factors which come into play during speaking tests, the differences between common test formats, and the challenge of ensuring equity in assessment, this book offers research-based advice on ways to design test tasks and in-depth insights into the assessment of L2 speaking. Featuring a glossary of key terms and concepts, discussion questions and further reading for each chapter, and a comprehensive companion website hosting a wealth of additional materials, including authentic test recordings and assessment tasks to be used by researchers and practitioners alike, this is the only book needed in order to understand, design, and assess interactive oral L2 tests.