A method for equating test scores between two standardized achievement testing programs was developed. The first test was the Survey of Basic Skills (SBS) published by Science Research Associates. The second was the Tests of Individual Performance (TIP) of the Portland Public Schools in Oregon. Scores reported in Rasch units (RIT) from the TIP administrations to a total of 1,918 students in the Tigard Oregon schools, grades 3 to 6, were matched to SBS item responses; and SBS tests were scaled (SCS scores) and linked to RIT scales using the fixed parameter method. There was a high level of consistency for the SCS/RIT conversion tables. The TIP RIT and SBS SCS scores provided comparable measures of reading and language achievement for these students. This study supports the possibility of vertically equating standardized test series in sequential subjects. Five figures are provided. (SLD)