Practitioners and researchers often review the validity evidence of an instrument before using it for student assessment or in the practice of diagnosing or identifying children with exceptionalities. However, few test manuals present data on instrument measurement equivalence/ invariance or differential item functioning. This information is critical as it allows the user to determine if the instrument yields equally valid information for a diverse group of children. This article presents the rationale and need for such information as well as a detailed process for how test developers, practitioners, or education researchers might complete their own evaluation of instrument invariance. (Contains 1 table.)