The unidimensionality of the reading and mathematics tests of the California Assessment Program was investigated. During April of 1980, all third grade students in California took a test consisting of reading, mathematics, and written language items. Item intercorrelation matrices were constructed for each skill, and the latent roots extracted. Methods of outlier analysis were applied to look for large drops in the size of the latent roots from each matrix. Mathematics skills tended to have smaller initial roots and a second root closer to the first than the reading skills. The evidence does not support the hypothesis of unidimensionality for the money and fractions skills, but does not contradict the hypothesis for the mathematical applications skill or for reading skills. (Author/BW)