Scores of two groups of White and Hispanic children at 11 age levels from 2.5 years to 12.5 years were assessed. The scores were drawn from the Kaufman Assessment Battery for Children (K-ABC), an individually administered assessment battery designed to measure intelligence and achievement and intended for minority group assessment. Reliability estimates were calculated on the K-ABC Mental Processing Scales using computed variance components. These estimates were compared as ratios of error variances and evaluated using F distributions. Ratios for the two groups at all age levels proved to be nonsignificant, indicative of statistically equivalent reliabilities for the two groups. Coefficients were, with two exceptions, similar in magnitude. While not a proof of "non-bias," this demonstration supports the notion that error in this instance is a function that is constant across groups. (Author/DWH)