Research on personality within the organizational sciences and for employee selection typically focuses on main effects, as opposed to interactive effects between personality variables. Large, multi-organizational datasets involving two different measures of personality were examined to test theoretically driven trait by trait interactions in predicting job performance. Interactive effects of Agreeableness and Conscientiousness, Agreeableness and Extraversion, Extraversion and Conscientiousness, and Emotional Stability and Conscientiousness were hypothesized as predicting overall job performance. However, these hypothesized effects were generally not supported. Implications for personality assessment are discussed.