This study investigated the relationship between the scales used for the NMSBA assessments and the RIT scales used to report performance on Northwest Evaluation Association tests. The study estimated the changes in reading and mathematics RIT score equivalents for the NMSBA performance levels in those subjects. Test records for more than 17,000 students were included in this study. performance levels. Rasch SOS methods generally produced the most accurate cut score estimates. Accuracy of predicting NMSBA proficient performance was well above 80% for all grades and subjects studied when using the best methodology. (Contains 26 tables and 8 figures.)