Leaders grow fastest when given accurate, detailed, and actionable information about the gap between their current skills and future potential. Companies seeking to create and channel development energy by providing this information often turn to assessment centers to gauge a leader's readiness for new job challenges. These assessment centers—which include "day in the life" simulations of what it's like to be a higher-level leader—are highly realistic, reliable, and predictive of future leadership success because they provide real opportunities to demonstrate leadership skills.