A taxonomy of covariance structure models for rep resenting multitrait-multimethod data is presented. Us ing this taxonomy, it is possible to formulate alternate series of hierarchically ordered, or nested, models for such data. By specifying hierarchically nested models, significance tests of differences between competing models are available. Within the proposed framework, specific model comparisons may be formulated to test the significance of the convergent and the discriminant validity shown by a set of measures as well as the ex tent of method variance. Application of the proposed framework to three multitrait-multimethod matrices al lowed resolution of contradictory conclusions drawn in previously published work, demonstrating the utility of the present approach.