High economic inequality negatively impacts nearly every aspect of human well-being—as well as the health of the biosphere. Contrary to intuition, it affects the wealthy and the middle classes, not just the poor. Here several leading researchers discuss these wide-ranging effects. Economist Joseph E. Stiglitz explains the origins of U.S. inequality and suggests measures to alleviate it. Political scientist Virginia Eubanks describes how digital systems often hurt, rather than help, the most vulnerable members of society. Neuroscientist Robert M. Sapolsky details the mechanisms by which inequality damages mental and physical health. And economist James K. Boyce describes how imbalances in economic and political power injure the environment—and how communities are coming together to combat such harm.