This paper discusses how to maintain the integrity of national normative information for achievement tests when the test that is administered has been customized to satisfy local needs and is not a test that has been nationally normed. Using an Item Response Theory perspective, alternative procedures for item selection and calibration are examined with respect to their effect on the accuracy of normative information. It is emphasized that it is important to match the content of the customized test with that of the normed test if accurate normative data are desired.