Are the traits that predict leadership emergence the same that predict leadership effectiveness? How do leader attributes play either a direct or dynamic role in predicting organisational outcomes? This paper presents an investigation into the personality-performance relationship to address these questions. 936 general population and 198 senior leadership participants took the High Potential Trait Indicator (HPTI). The first part examined how levels of personality traits differentiated leaders from a general population. The second examined the relationship between leader personality, competencies and organizational success to assess whether the traits of leader emergence are the same as effectiveness. Additionally, this section simultaneously examined the role of leader traits and attributes play in predicting organizational performance. The results indicated that all six HPTI traits were associated with leader emergence. However, only three-Adjustment, Risk Approach, and Ambiguity Acceptance-were also positively predictive of leadership effectiveness. Curiosity showed mixed benefits for leaders, whilst Conscientiousness and Competitiveness did not differentiative leader effectiveness. Additionally, leader attributes were found not to predict performance. This paper offers novel insight into the important role of personality in distinguishing leader emergence as well as leader effectiveness. Implications are discussed in relation to models of leadership and potential, as well as for practice include identifying high potential talent and diversity in psychometric testing.