A practical application of generalizability theory, demonstrating how the variance components contribute to understanding and interpreting the data collected to evaluate a program, is described. The evaluation concerned 120 learning modules developed for the Dental Auxiliary Education Project. The goals of the project were to design, implement, and evaluate an innovative curriculum for dental assistants and dental hygienists. A repeated measures design was developed in which students were nested within schools which were crossed with modules and items. Generalizability theory allows for direct comparison of the relative magnitude of the sources of variance in the study design, as well as calculation of a variety of useful generalizability coefficients indicating the relative degree of accuracy with which the investigator can generalize across factors. It allows an assessment of the efficiency of the design in that it is possible to assess changes in generalizability coefficients with changes in numbers of subjects, items, groups, etc. (PN)