Every year America becomes more diverse, but change in the makeup of the management ranks has stalled. The problem has become an urgent matter of national debate. How do we fix it? Arguing that it's time to focus on changing systems rather than individuals, two of the world's leading experts on workplace diversity show us a better way in the first comprehensive, data-driven analysis of what succeeds and what fails. The surprising results will change how America works. Frank Dobbin and Alexandra Kalev draw on more than thirty years of data from eight hundred companies as well as in-depth interviews with managers. The research shows just how little companies gain from standard practice: sending managers to diversity training to reveal their biases, then following up with hiring and promotion rules, and sanctions, to shape their behavior. Almost nothing changes. It's time, Dobbin and Kalev argue, to focus on changing the management systems that make it hard for women and people of color to succeed. They show us how the best firms are pioneering new recruitment, mentoring, and skill training systems, and implementing strategies for mixing segregated work groups to increase diversity. They explain what a difference ambitious work-life programs make. And they argue that as firms adopt new systems, the key to making them work is to make them accessible to all.