Curriculum-Based Assessment for Instructional Design (CBA-ID) provides data used to ensure an appropriately challenging learning task. One aspect of appropriate challenge measured by CBA-ID, called the acquisition rate (AR), involves the amount of new information a student could acquire and retain during initial learning. Previous research suggested adequate reliability, consistency with theory, expected developmental changes, and instructional utility, but the correlation between CBA-ID data and criterion variables has not been examined. Criterion-related validity coeffi cients could be an important source of data with which validity of CBA-ID data can be evaluated. The current study examined the criterion-related validity of assessing ARs with CBA-ID by correlating acquisition rates with scores from the Test of Memory and Learning (TOMAL) for 25 students in third and fourth grade. Corrected coefficients were equal to or exceeded .70 for two of the three TOMAL indices and equaled .59 for the third. Thus, these data supported the criterion-related validity of measuring ARs with CBA-ID.