Content, instructional, and curricular validity, as related to certification tests, are examined. All three deal with content validity but the domain differs among the the three. Certification tests must have instructional validity, i.e., the test must be valid both with respect to the domain used to define the minimum competencies and the instructional content domain (what is taught in the schools). The test items must be representative of the objectives domain but not necessarily representative of the instructional content domain. Whether a test has content validity with respect to the domain specified by the curricular materials is important only insofar as it is a surrogate for instructional validity. Curricular validity should not be used as a criterion to establish the instructional validity of a certification test. For tests of certification, a relatively large percentage of the items should represent topics that are covered by all students in the district and/or state (to assure that certification tests have instructional validity). A prototypic measurement of curricular and instructional validity for elementary school mathematics illustrates these points. (Author/PN)