Content validation is a crucial, but often neglected, component of good test development. In the present study, content validity evidence was collected to determine the degree to which elements (e.g., grammatical structures, items, picture responses, administration, and scoring instructions) of the Comprehension of Written Grammar (CWG) test are representative of the construct of interest and appropriate for deaf and/or hard of hearing (DHH) students. Using 10 subject matter experts (SMEs) and the Content Validity Index, the quantitative findings showed general support for the content validity of elements of the CWG in assessing the written grammar comprehension of DHH students. Suggested revisions to the test, based on the feedback provided by the SMEs, are discussed.