Identifying the susceptibility of an aggregate to the alkali-silica reaction (ASR) before using it in concrete is one of the most efficient practices for preventing damage. ASTM C 1260 (Mortar-Bar Test) and ASTM C 1293 (Concrete-Prism Test) have been used to identify ASR-susceptible aggregates. ASTM C 1260 modifications consisted of performing the test using different NaOH solution normalities, namely, 1N, 0.75N, and 0.25N. ASTM C 1293 modifications consisted of increasing the storage temperature from 38 deg C to 60 deg C and storing the concrete prisms in 1N NaOH solution at 38 deg C. The evaluation, comparison, and results for these two tests and their suggested modifications are presented. Data indicate that the levels of test results suggested in the nonmandatory information in the appendix to ASTM C 1260 as "potentially deleterious" are achieved by many aggregates with a good service record. Results suggest that ASTM C 1260 should be used in combination with ASTM C 1293. The nonmandatory information in the appendix to ASTM C 1293 on levels of expansion that should be regarded as potentially deleterious is less likely to be exceeded by aggregates with good service records than in the case of those in the appendix to ASTM C 1260. Changes in the solution normality of the ASTM C 1260 test could be used to evaluate the effect of the alkali content on ASR but do not alleviate the severity of the test for the aggregates investigated. ASTM C 1293 could be effectively accelerated to generate results within 3 months instead of 1 year by increasing the testing temperature from 38 deg C to 60 deg C.