Can economics be passionate?… Can it center on people and what really matters to them day-in and day-out.… And help us understand their hidden motives for why they do what they do in everyday life? Uri Gneezy and John List are revolutionaries. Their ideas and methods for revealing what really works in addressing big social, business, and economic problems gives us new understanding of the motives underlying human behavior. We can then structure incentives that can get people to move mountains, change their behavior—or at least get a better deal. But finding the right incentive can be like looking for a needle in a haystack. Gneezy and List’s pioneering approach is to embed themselves in the factories, schools, communities, and offices where people work, live, and play. Then, through large-scale field experiments conducted “in the wild,” Gneezy and List observe people in their natural environments without them being aware that they are observed. Their randomized experiments have revealed ways to close the gap between rich and poor students; to stop the violence plaguing inner-city schools; to decipher whether women are really less competitive than men; to correctly price products and services; and to discover the real reasons why people discriminate. To get the answers, Gneezy and List boarded planes, helicopters, trains, and automobiles to embark on journeys from the foothills of Kilimanjaro to California wineries; from sultry northern India to the chilly streets of Chicago; from the playgrounds of schools in Israel to the boardrooms of some of the world’s largest corporations. In The Why Axis, they take us along for the ride, and through engaging and colorful stories, present lessons with big payoffs. Their revelatory, startling, and urgent discoveries about how incentives really work are both revolutionary and immensely practical. This research will change both the way we think about and take action on big and little problems. Instead of relying on assumptions, we can find out, through evidence, what really works. Anyone working in business, politics, education, or philanthropy can use the approach Gneezy and List describe in The Why Axis to reach a deeper, nuanced understanding of human behavior, and a better understanding of what motivates people and why.