This construct validation study investigated the factor structure of the Test of English as a Foreign Language[TM] Internet-based test (TOEFL[R] iBT). An item-level confirmatory factor analysis was conducted for a test form completed by participants in a field study. A higher-order factor model was identified, with a higher-order general factor (ESL/EFL ability) and four first-order factors for reading, listening, speaking and writing. Integrated Speaking and Writing tasks, which require language processing in multiple modalities, defined the target modalities (speaking and writing). These results broadly supported the current practice of reporting a total score and four scores corresponding to the modalities for the test, as well as the test design that permits the integrated tasks to contribute only to the scores of the target modalities. (Contains 1 footnote, 4 tables, and 5 figures.)