This study compared the underlying factors measured by a state standards-based grade 4 English-Language Arts (ELA) assessment given to several groups of students. The focus of the research was to gather evidence regarding whether or not the tests measured the same construct or constructs for students without disabilities who took the test under standard conditions, students with learning disabilities who took the test under standard conditions, students with learning disabilities who took the test with accommodations as specified in their Individualized Educational Program (IEP) or 504 plan, and students with learning disabilities who took the test with a read-aloud accommodation/modification. The ELA assessment contained both reading and writing portions. A total of 75 multiple-choice items were analyzed. A series of nested hypotheses were tested to determine if the ELA measured the same factors for students with disabilities who took the assessment with and without accommodations and students without disabilities who took the test without accommodations. The results of these analyses, although not conclusive, indicated that the assessment had a similar factor structure for all groups included in the study. (Contains 8 tables, 2 figures, and 3 footnotes.)