Use of item response theory (IRT), the delta plot method, and Mantel-Haenszel techniques to assess differential item functioning (DIF) across racial and gender groups associated with the Maryland Test of Citizenship Skills (MTCS) is described. The objective of this research was to determine the: effect of sample size on results from these three DIF techniques; degree of relationship among these DIF statistics; and degree to which they identify the same items as biased. The data for the study include item responses from one form of the 1988 edition of the MTCS. The MTCS consists of 45 multiple-choice items that assess students' knowledge and skills in 3 domains: constitutional government; politics and political behavior; and principles, rights, and responsibilities. The MTCS was administered to 50,000 ninth graders during January and February of 1988. The analyses were performed on representative samples of 1,000, 750, 500, and 200 first-time test takers. It is concluded that no MTCS items are functioning differentially in either black/white or male/female comparisons. Plots of item difficulty estimates for black/white and male/female comparisons show nearly perfect linear relationships in both groups. Agreement, as indicated by rank order correlations across DIF techniques, is very high between Rasch and Delta Plot DIF indices for all sample sizes in both black/white and male/female comparisons. In terms of agreement regarding biased and unbiased items, agreement with the three-parameter DIF index is highest for the Delta Plot and Rasch techniques. A 30-item list of references, 19 data tables, and 30 figures are included. (TJH)