This study examines the effects of two test administration accommodations on the mathematics performance of students within the context of a large-scale statewide assessment. The two test administration accommodations were resource guides and calculators. A stratified random sample of schools was selected to represent the demographic characteristics of the state. The sample included both students with and without disabilities. Schools were randomly assigned to one of three possible administration conditions: resource guides, calculators, or standard administration. A repeated-measures design (pretest and posttest) was used to examine the effects of the accommodations. Students in the participating schools took the operational version of the statewide assessment in grades 3 and 6 in the spring of 2005, and then were retested in grades 4 (N = 947) and 7 (N = 997) with the same form of the test under one of the three administration conditions in the spring of 2006. The results of this study suggest that the use of resource guides were not effective. The results for the use of calculators as a test administration accommodation were somewhat mixed with both small positive and small negative effects sizes varying by grade. Exploratory analyses on subgroups of students with various disabilities suggest that there may be small positive benefits for some students in some disability categories under some accommodated conditions. (Contains 4 tables and 2 figures.)