Throughout its long history, sulfate soundness testing of aggregates has been frequently cited for poor reliability as a predictor of concrete durability. However, its use remains widespread, even to the point of constituting an acceptance test criterion for aggregates. Sodium sulfate soundness tests of coarse aggregates are compared in this paper with freezing and thawing tests of air-entrained concretes containing the aggregates. In one case, sodium sulfate soundness displayed a relationship to durability (freezing and thawing) test results, in a statistical sense, but the level of predictability was poor. In another test series, the level of predictability fell within the range of pure chance.