Experiments have consistently been used in the hard sciences, but in recent decades social scientists have adopted the practice. Randomized trials have been used to design policies to increase educational attainment, lower crime rates, elevate employment rates, and improve living standards among the poor.

This book tells the stories of radical researchers who have used experiments to overturn conventional wisdom. From finding the cure for scurvy to discovering what policies really improve literacy rates, Leigh shows how randomistas have shaped life as we know it. Written in a "Gladwell-esque" style, this book provides a fascinating account of key randomized control trial studies from across the globe and the challenges that randomistas have faced in getting their studies accepted and their findings implemented. In telling these stories, Leigh draws out key lessons learned and shows the most effective way to conduct these trials.