Differential item functioning (DIF) analysis is a statistical technique used for ensuring the equity and fairness of educational assessments. This study formulates a new DIF analysis method using the information similarity index (ISI). ISI compares item information functions when data fits the Rasch model. Through simulations and an international assessment example, ISI, the signed area index (SAI), and Mantel-Haenszel procedure, are compared. Results show that in many circumstances, ISI performs comparably, if not better than MH and SAI in terms of its capacity to detect DIF. Additionally, guidelines for assessing practically and statistically significant DIF using ISI are provided. (Contains 2 notes, 6 tables, and 2 figures.)