Abstract
Content validity has been defined as the formal specification of the universe of tasks the test purports to measure. The universe of tasks consists of both the subject matter of the instrument and the structure of the instrument. However, it has been observed that instrument structure is often overlooked in the development and validation of achievement tests. A review of the research on item writing, item format, test instructions, and item readability indicated the importance of instrument structure in the interpretation of test data. The effect of failing to consider these areas on the content validity of achievement test scores was discussed.