Using trait activation theory as a framework, the authors examined the moderating role of two situational variables-perceptions of organizational politics and perceptions of leader effectiveness-on the relationship between core self-evaluations and job performance. Results from two samples (N = 137 and N = 226) indicate that employee perceptions of their work environment moderated the relationship between their core self-evaluations and supervisor ratings of their performance. In particular, those with higher core self-evaluations received higher performance ratings in environments perceived as favorable than in environments perceived as unfavorable.