Two new methods for improving the measurement precision of a general test factor are proposed and evaluated. One new method provides a multidimensional item response theory estimate obtained from conventional administrations of multiple-choice test items that span general and nuisance dimensions. The other method chooses items adaptively to maximize the precision of the general ability score. Both methods display substantial increases in precision over alternative item selection and scoring procedures. Results of a simulation study based on the Armed Services Vocational Aptitude Battery suggest that the use of these new testing methods may significantly enhance the prediction of learning and performance in instances where standardized tests are currently used. (Contains 5 tables, 1 figure, and 44 references.) (SLD)