Background: This study examined the comparability of reading and writing tasks of two English language proficiency tests—the General English Proficiency Test-A (GEPT-A) developed by Language Training Center, Taipei and the Internet-Based Test of English as a Foreign Language (iBT) developed by Educational Testing Service, Princeton. Methods: Data was collected from 184 test takers, 92 in Taiwan and 92 in the USA. Three specific analyses were conducted: First, a content analysis was performed on the passages in the GEPT-A and on the iBT reading passages. Second, a task analysis of the construct coverage, scope, and task formats used in the reading sections, and third, a test performance analysis of scores on the two tests were conducted. Results: The results of the text analysis showed the reading passages on the two tests are comparable in many ways but differ in several key regards. The task analysis revealed that the construct coverage, item scope, and task formats of the two tests are clearly distinct. Analysis of test performance showed that scores on the GEPT-A and iBT are highly inter-correlated with each other. Exploratory and confirmatory factor analyses of the test score data indicated that the two tests appeared to be measuring reading and writing ability but emphasize different aspects of the reading construct. Conclusion: Although the two tests are comparable in many ways, the reading passages differ in several key regards. Analyses of participant responses indicated that the two tests assess the same reading construct but emphasize different aspects of it.