Abstract The aim of the present research is to examine the viability of the construct
validity of the speaking modules of two internationally recognized language proficiency
examinations, namely IELTS and TOEFL iBT. High-stake standardized tests
play a crucial and decisive role in determining the future academic life of many
people. Overall obtained scores of candidates are believed to reflect their general
proficiency level. Appropriate interpretation and use of test scores depend on the
extent to which items measuring a particular skill (here speaking) can meet the criteria
to examine the intended construct. Speaking, amongst the other four skills, has a
central place in assessing general proficiency of the candidates. This research seeks to
scrutinize how IELTS and TOEFL iBT tap on the speaking proficiency of their
candidates. Moreover, this study investigates whether obtained speaking scores of
candidates in these two international high-stake tests show an acceptable degree of
consistency in measuring the skill being examined. The chosen sample of the study
consisted of 60 students who successfully completed TOEFL iBT and IELTS preparation
courses in Tehran. The results of the statistical analysis show that there is a
meaningful discrepancy between the two exams in assessing the speaking abilities of
the exam-takers and therefore challenge the construct validity of the exams in
question. Findings are then used to discuss the repercussions for language proficiency
measurement and assessment.