Introduction
InternationalEnglish Language Testing System (IELTS) was established in 1989. Todate, fifteen rounds of research designed to improve the test have been jointlycommissioned by the British Council, the University of Cambridge English for Speakers of Other Languages (ESOL) Syndicate, and theInternational DevelopmentProgram of Australian Universities and Colleges (IDP). These projects have examinedvery diverse aspects of the test, from the language testing theory underpinning it totest taker attitudes and classroom training methods. As a result of this research, thetest has undergone changes, and the IELTS of 2010 is quite different from the IELTSof 1989.Today, many universitieswhose medium of instruction is Englishhaveadopted IELTS as an entry requirement fornon-native English speakers. Manyrequire a score of at least six out of nine on the test as a threshold of minimum proficiency. Students with lower scores may be refused admission or asked to takesupplementary English language programs even if they havealready demonstratedother qualifications.In the present study, I review existing research on the IELTS Speaking andListening modules, and create a unitary structure of validity arguments that organizesthe results of this research. This synthesis willhelp spot weak areas and direct futureattempts to bridge existing gaps.This article proceeds as follows: It briefly reviews the history of the validityconcept and validity arguments; provides an overview ofthe Speaking Module,including its analytic scoring system, the role of examiner judgment,its structure, theRevision Programs and impact studies, and some miscellaneous topics; highlights the paucity of research on the Listening Module;explains the interpretive arguments of the IELTS Speaking and Listening modules and investigates their plausibility using