This study investigated the convergent validity of expert-system scores for four mathematical constructed-response item formats. A five-factor model was proposed comprised of four constructed-response format factors and a Graduate Record Examinations (GRE) General Test quantitative factor. Subjects were drawn from examinees taking a single form of the GRE General Test in June 1989. The final study sample consisted of 249 test takers. Confirmatory factor analysis was used to test the fit of this model and to compare it with several alternatives. The five-factor model fit well, although a solution comprised of two highly correlated dimensions--GRE quantitative and constructed-response--represented the data almost as well. These results extend the meaning of the expert system's constructed-response scores by relating them to a well-established quantitative measure and by indicating that they signify the same underlying proficiency across item formats. Appendices present test item stems, the scoring rubrics, and an estimated correlation matrix. (Contains 1 figure, 8 tables, and 34 references.) (Author/SLD)