This study presents a meta-analysis of 25 individual differences proposed to be related to effective leadership, with an emphasis on comparing trait-like (e.g. personality and intelligence) to state-like individual differences (e.g. knowledge and skills). The results indicate that although both trait-like (achievement motivation, energy, dominance, honesty/integrity, self-confidence, creativity, and charisma) and state-like (interpersonal skills, oral communication, written communication, administrative/management skills, problem-solving skills, and decision making) individual differences were consistent predictors of effective leadership, the impact of trait-like and state-like individual differences was modest overall and did not differ substantially (ρ= .27 and .26, respectively). Finally, organizational level of the leader, method of predictor and criterion measurement, and organization type moderated the relationship between individual differences and effective leadership.