What does it take to become an expert? A popular writer cites the “10,000-hour rule.” According to this rule, if you practice for 10,000 hours, you will become an expert. But this rule is an oversimplification of important research: in fields as diverse as music, math, and leadership, deliberate practice is the only kind of practice that promises to produce excellence. 10,000 Hour Rule In his best-selling book Outliers, Malcolm Gladwell cited studies on expert violinists to promote the “10,000-hour rule.” He used Mozart as a prime example. Mozart learned to play at the age of four. Despite his musical genius – both as a performer and a composer – he practiced for thousands of hours to cultivate his art while other boys played with toy soldiers. So Gladwell does get the general concept correctly. To become an expert in any discipline – even for those with latent talent – takes tons of practice. But not all practice is equal.