We often hear about the power of personality, and how some traits are beneficial for our careers while others are more harmful. For example, we know that being more conscientious (hard-working, driven, reliable, and organized) is associated with better job performance, and that being nice (more agreeable) does not pay off in wages. But it is less clear when these personality traits matter most for our careers — are they more important earlier on, or in the middle? — and who benefits most from them.