One of the most prevalent and controversial accommodations for students with disabilities is an audio presentation of written test material, the "read-aloud" accommodation. This study used test administration data from the Missouri Assessment Program to examine effects of using the read-aloud accommodation on the characteristics of multiple-choice math and reading test items administered to approximately 3200 students in 3rd and 4th grades. Four subject groups were defined: non-accommodated students with no disabilities; non-accommodated students with no disabilities matched in test performance to students with a reading disability; non-accommodated students with a reading disability; and students with a reading disability who took the test with the read-aloud accommodation. Differential item function (DIF) analysis was used to determine numbers of difficult items for each group. Significantly more DIF items were identified for students receiving the read aloud accommodation than for similarly disabled students tested without the accommodation, suggesting that the read-aloud accommodation is ineffective for students with reading disabilities or that a reading test measures the reading construct differently for students with a reading disability than for students without disabilities. Appendices present detailed test results. (Contains 13 references.) (DB)