What Social Justice is a concept which concerns key issues of our time: equality, equity, solidarity, care, and inclusion. However, across nations and social groups people have different ideas about the morally appropriate level and form of social justice and who they consider responsible for ensuring social justice. This book investigates these differences to uncover how people make sense of social justice and what moral principles they think justifies their personal ideal of social justice. The book pursues the thesis that people fundamentally share moral principles of social justice but may apply these principles differently, based on cultural notions of the good society and the good life particular to a specific national or class context. Why Social justice is the topic of heated public debate regarding economic inequality, unequal access to education, health inequalities and sustainable development. The debate is, however, largely a conversation among political and economic elites and based in polarized, elite interests and notions of the just and good society. What social justice means to ordinary people, how they think resources, burdens and opportunities should be distributed, and what moral principles they subscribe to, remains largely unknown. The book Just and Unjust Worlds present evidence that while popular notions of social justice may superficially differ due to cultural and institutional context, fundamental moral principles of social justice are shared across contexts. How The book presents a comprehensive theory of social justice as a subjectively meaningful issue on which ordinary people make competent, moral judgment. It provides a framework for analysing how social justice judgements draw on specific moral principles. The monograph is based on a unique mixed methods dataset integrating 280 comparative, qualitative interviews on social justice from China, USA, Denmark, and Sweden with comparative survey data on social justice attitudes from the Worlds Values Survey and the European Values Study. Interview data was collected among middle class and working-class people in two comparable, urban contexts within each country. SSR Current research and elite debates on social justice tends to focus on differences and polarizations, obscuring the shared moral principles and aspirations of ordinary people. This exaggeration of differences means that the field of potential consensus, compromise, and public legitimacy is underestimated. This project gives voice to non-elite notions of social justice and identify some fundamental requirements for the good life and the good society as they exist outside of elite discourse. Social justice will likely become an increasingly important and contested issue in the coming years, not least due to rapid increases in economic and social inequalities and to the mounting tensions between calls for social justice and calls for climate action. The book will inform publics, policy makers and academics alike and help identify the common grounds on which to build social justice for the future.