The sort of coaching that fosters effective innovation and judgment, not merely the replication of technique, may not be so easy to cultivate. Yet modern society increasingly depends on ordinary people taking responsibility for doing extraordinary things: operating inside people’s bodies, teaching eighth graders algebraic concepts that Euclid would have struggled with, building a highway through a mountain, constructing a wireless computer network across a state, running a factory, reducing a city’s crime rate. In the absence of guidance, how many people can do such complex tasks at the level we require? With a diploma, a few will achieve sustained mastery; with a good coach, many could. We treat guidance for professionals as a luxury—you can guess what gets cut first when school-district budgets are slashed. But coaching may prove essential to the success of modern society.