this studyinvestigated therelations between examinees’ academic knowledge and theirperformanceonreading section of ielts and toefl (ibt) through using generalizabilitytheory. g-theory was utilized to investigate the effects of subtest, test items, participants and academic background on the reliability of ielts and toefl (ibt) score. tosamplethe subjectsofthissurvey,a placement testwasadministered to119studentsstudyingat intermediatelevelof ielts and toefl preparatory courses. 96 of them passed the testandwere put in the three academic background groups, humanities, natural sciences and mathematics, and were given the reading tests.