The purpose of this study was to introduce a procedure to detect differential item functioning (DIF) particularly suitable for criterion-referenced tests and to demonstrate how this approach would affect the identification of DIF items using real data sets. The procedure based on item response theory (IRT) assesses DIF at a limited closed interval of thetas at which a cutoff score fails. Illustrative data showed that identification of DIF could be quite different with this unconventional procedure as opposed to traditional DIF measures with which DIF was assessed over the entire range of ability. It was recommended that test development practitioners be actively involved in the DIF analysis to investigate not only if an item is biased, but where it may be biased. Three figures, and five tables are included. (Contains 8 references.) (Author)