Inequality in society is not a new phenomenon. And yet it can be fatal. If left unchecked, as demonstrated in this Report, it can undermine the very foundations of development and social and domestic peace.

Over the last decades, the world has witnessed impressive average gains against multiple indicators of material prosperity. For instance, gross domestic product (GDP) per capita in low- and middle-income countries has more than doubled in real terms since 1990. In the same period, life expectancy in developing countries has risen from 63.2 years to 68.6 years. However, this is only part of the picture. Although the world is globally richer than ever before, more than 1.2 billion people still live in extreme poverty. The richest 1 percent of the world population owns about 40 percent of the world’s assets, while the bottom half owns no more than 1 percent. Despite overall declines in maternal mortality, women in rural areas are still up to three times more likely to die while giving birth than women living in urban centres. Social protection has been extended, yet persons with disabilities are up to five times more likely than average to incur catastrophic health expenditures. Women are participating more in the work force, but continue to be disproportionately represented in vulnerable employment. Humanity remains deeply divided.

Millions of voices are asking the world’s decision makers to confront rising inequalities. It is imperative that this demand be met if the ideals of a prosperous, peaceful and sustainable society are to be realized.

This Report reviews the conceptual approaches that have been adopted in the analysis of inequality and explains why inequality matters. It also examines trends and drivers of inequality in income and non-income dimensions of well-being as well as the trends and drivers of gender inequality as an example of intergroup inequality. After illustrating the results of an investigation of policy makers’ views of inequality, it concludes with a comprehensive policy framework to confront inequality in developing countries.