The authors present results of 4 studies that seek to determine the discriminant and incremental validity of the 3 most widely studied traits in psychology-self-esteem, neuroticism, and locus of control-along with a 4th, closely related trait-generalized self-efficacy. Meta-analytic results indicated that measures of the 4 traits were strongly related. Results also demonstrated that a single factor explained the relationships among measures of the 4 traits. The 4 trait measures display relatively poor discriminant validity, and each accounted for little incremental variance in predicting external criteria relative to the higher order construct. In light of these results, the authors suggest that measures purporting to assess self-esteem, locus of control, neuroticism, and generalized self-efficacy may be markers of the same higher order concept.