The issue discussed in this paper is how to test bilingual education teachers in order to be sure that they can teach bilingually in subject areas such as mathematics, science, or social studies. Four aspects of the question are discussed with reference to Spanish/English bilingual education, with the understanding that most questions raised are pertinent to most of the other languages encompassed within the bilingual education movement. The four aspects are: (1) a discussion of the issue of the appropriate language variety or register for assessment of the bilingual subject area teacher, including consideration of "world standard Spanish" and the varieties of Spanish characteristic of different parts of the United States; (2) a review of issues dealing with test formats for assessing the subject area teacher, especially the debate over natural communication versus linguistic manipulation tasks; (3) an introduction to the ideal qualities that an assessment instrument should have; and (4) the problem of vocabulary which in much of the content areas has been borrowed from English into Spanish and has been translated in a variety of ways by different speakers. It is concluded that the language register problem and the connected lexical problem in Spanish are not yet resolved. (AMH)