Since SLA literature remains researchers unaware of the mental processes involved in the X-Test taking (in contrast to C-Test which there are plenty of available related studies), this article aims at exploring cognitive strategies that EFL learners may use while answering an English X-test, which like the C-Test has been modified, adapted and used in many research papers. To this aim, thirty EFL respondents from Mashhad, Iran, were randomly asked to answer a reliable and valid X-test. All of them participated in introspective methods of think-aloud and retrospective interviews during and after the test administration. To analyze the data only the exact word scoring procedure was employed. The results showed participants used various cognitive strategies in taking the X-Test. It was also revealed that respondents experienced more strategies when filling out an X-Test comparing to related literature of C-test, which could be an indicator of the importance job of cognition in X-Test taking. It is hoped that the article can shed light on the underling cognitive strategies that English language learners' use, and provide a chance for educators who want to better understand the learners' cognitive processes in order to assist them identify problems and improve their English instruction.