The current study examined the incremental validity of the Luria interpretive scheme for the Kaufman Assessment Battery for Children-Second Edition (KABC-II) for predicting scores on the Kaufman Test of Educational Achievement-Second Edition (KTEA-II). All participants were children and adolescents (N = 2,025) drawn from the nationally representative KABC-II/KTEA-II linked standardization sample. Consistent with previous studies, the full scale Mental Processing Index (MPI) score accounted for clinically significant portions of KTEA-II score variance in all of the regression models that were assessed. In contrast, the Luria factor scores collectively failed to provide meaningful incremental predictive variance after controlling for the effects of the MPI. Individually, the factor scores consistently accounted for trivial portions of achievement variance. Potential implications of these results for the correct interpretation of the KABC-II within clinical practice are discussed.