Never before has inequality been so high on the agenda of policy-makers worldwide, or such a hot topic for social science research. More journal articles are being published on the topic of inequality and social justice today than ever before. This Report draws on the insights of over 100 social scientists and other thought leaders from all over the world, across various disciplines, to emphasize transformative responses to inequality at all levels, from the grass roots to global governance. Too many countries are investing too little in researching the long-term impact of inequality on the sustainability of their economies, societies and communities. Unless we address this urgently, inequalities will make the cross-cutting ambition of the Sustainable Development Goals (SDGs) to ‘leave no one behind’ by 2030 an empty slogan.