This paper focuses on the development of the Japanese-English Bilingual Grammar Test(JEBGT, henceforth), which is intended to measure Japanese EFL learners’ grammatical ability in relation to extensive reading in English. The paper starts with the rationale for developing the JEBGT: the lack of previous studies of the effects of extensive reading on the development of grammatical ability and the lack of instruments which measure grammatical ability with independent tasks. The test specifications, the principles for item writing, specifications of the Overall Test Structure, and specifications for individual tasks were made. After a small-scale pilot study, minor revisions were made. Then, the JEBGT was administered to 450 Japanese EFL learners at the university level. The test data was Rasch analyzed and the findings were presented.研究論文JSPS 科研費24520678、15K0280
