A review of the literature regarding behavioral characteristics and underlying factors for behaviorally disordered (BD) students revealed that both elementary school aged and secondary school aged BD students may be able to be described by a similar factor structure. Utilizing ratings obtained on a national sample of BD students with the Behavioral Dimensions Rating Scale (BDRS). Research Edition, the pattern of item ratings for students in grades kindergarten through five (K-5) and grades six through eleven (6-11) was examined to confirm this literature-based theory. Multigroup simultaneous confirmatory factor analysis using maximum likelihood estimation procedures was utilized to compare the covariance structures of students in grades K-5 and grades 6-11. A goodness-of-fit index revealed that the covariance matrices of the two groups were invariant. Since the same factor structure could be used to describe BD students in grades K-5 and grades 6-11, the means for the two groups were compared using Hotelling's T^2 statistic for two independent samples. The analysis resulted in finding a significant difference between the two groups' means. A univariate F test was conducted for the behavioral dimensions to locate the source of the mean difference. A significant difference was found only for Factor I: Aggressive/Acting Out, indicating …