The Woodcock-Johnson Psycho-Educational Battery (W-J) is a norm-referenced device combining measures of cognitive ability, achievement, and interest. The battery was developed using both factor analysis and multiple-regression analysis to determine differential weighting systems and derive factor clusters. The present discussion is a critical evaluation of the usefulness of the battery for the assessment of learning disabled (LD) students. Data on 50 learning disabled fourth-grade students were used to investigate the logical consistency and external validity of the Woodcock-Johnson. Based on the above data, the W-J factor clusters could not be replicated in this sample of learning disabled students; also, little evidence was found of the validity of either the cognitive factor clusters or the aptitude factor clusters. Major questions are raised regarding subtest overlap and especially suppressor variables, as well as operationalization of the aptitude clusters.