This document discusses leadership development and summarizes research findings from analyzing 360-degree feedback and performance metrics from over 20,000 managers. Some key findings include: 1) Leadership development has focused too much on fixing weaknesses rather than developing strengths; 2) Extraordinary leaders have profound strengths in a few key areas rather than being good at many things; 3) Organizations should focus development on good managers to help them become great rather than just the bottom or top performers.