Anthony Green’s new bookExploring Language Assessment and Testing: language in action is one of the Routledge Introductions to Applied Linguistics published in 2014. The book provides teachers and testers with practical guides by interpreting the place, purposes, principles, multiple approaches and current trends of language assessment and testing, which is designed to offer a comprehensive discussion on essential principles and their application in practice. The PRICE principles，the assessment cycle，the causes and effects of washback，and the six phases in language assessment are put forward. This paper introduces the book and comments on its merits and demerits as well.