This paper explains the workings of a new test developed to assess the vocabulary size of Japanese learners of English. Five thousand of the most-frequently-used English vocabulary (JACET: 1993) have been grouped into five levels. All vocabulary items within a particular multiple-choice question utilize only vocabulary located at that level or below. If a student answers 80% or more correctly, the student is thought to be proficient at that level, and can then aim for the next higher level. The test has several good points. First, students can understand their present English vocabulary abilities. Second, students can set clear goals for themselves. Third, the test is easy and fast to administer and to score. Fourth, it measures not only receptive skills but also productive skills. Finally, it can be used either by teachers in classrooms, or by students doing independent study.