This edited volume develops a theoretical framework for validating tests of second language ability. The chapter authors show how an understanding and analysis of the framework and its components can assist test developers to operationalise their tests more effectively, especially in relation to the key criteria that differentiate one proficiency level from another. The book provides an up-to-date review of the relevant literature on assessing speaking, an accessible and systematic description of the different proficiency levels in second language speaking and a comprehensive and coherent basis for validating tests of speaking. It will be of considerable interest to examination boards who wish to validate their own speaking tests in a systematic and coherent manner, as well as to academic researchers and graduate students in the field of language assessment more generally.