Each year, Montana students participate in testing as part of the state's assessment program. This past spring, students in grades 4, 8, and 10 took Montana Comprehensive Assessment System (MontCAS) tests in reading and mathematics. These tests serve as an important measure of student achievement for the state's accountability system. Results from these assessments are used to make state-level decisions concerning education, to meet "Adequate Yearly Progress" (AYP) reporting requirements of the "No Child Left Behind Act" (NCLB), and to inform schools and school districts of their performance. The Montana Office of Public Instruction has developed scales that are used to assign students to one of four performance levels on these tests. Many students who attend school in Montana also take tests developed in cooperation with the Northwest Evaluation Association (NWEA). The content of these tests are aligned with the Montana standards and they report student performance on a single, cross-grade scale, which NWEA calls the RIT scale. This study investigated the relationship between the scales used for the MontCAS assessments and the RIT scales used to report performance on NWEA tests. The study estimated the changes in reading and mathematics RIT score equivalents for the MontCAS performance levels in those subjects. Test records for more than 4,000 students were included in this study. Three methods generated an estimate of RIT cut scores that could be used to project MontCAS performance levels. Rasch SOS methods generally produced the most accurate cut score estimates. Accuracy of predicting MontCAS passing performance was well above 80% for all grades and subjects studied when using the best methodology. (Contains 14 tables and 5 figures.)