Using 3 different samples, the authors assessed the incremental validity of situational judgment inventories (SJIs), relative to job knowledge, cognitive ability, job experience, and conscientiousness, in the prediction of job performance. The SJI was a valid predictor in all 3 samples and incrementally so in 2 samples. Relative to the other predictors, SJI's partial correlation with performance, controlling for the other 4 predictors, was superior in most comparisons. Subgroup differences on the SJI also appear to be less than those for cognitive ability and job knowledge, but greater than differences in conscientiousness. The SJI should prove to be a valuable additional measure in the prediction of job performance, but several additional areas of research are suggested.