From the United States to the United Kingdom and from China to India, growing inequality has led to social discontent and the emergence of populist parties, also contributing to economic crises.We urgently need a better understanding of the roots and costs of these income gaps.The Costs of Inequality draws on the experience of Latin America, one of the most unequal regions of the world, to demonstrate how inequality has hampered economic growth, contributed to a lack of good jobs, weakened democracy, and led to social divisions and mistrust.In turn, low growth, exclusionary politics, violence and social mistrust have reinforced inequality, generating various vicious circles.Latin America thus provides a disturbing image of what the future may hold in other countries if we do not act quickly.It also provides some useful lessons on how to fight income concentration and build more equitable societies.