This chapter traces how ‘sustainability movement’ we see today was made. It reviews how modern sustainability thinking emerged from scientific insights into Earth’s limits and humanity’s development ambitions. It introduces the “planetary boundaries framework”, which shows that seven of nine environmental thresholds—such as climate change, biodiversity loss, and nitrogen cycles—are already exceeded, underscoring the systemic risks facing economies and societies. The chapter then connects these biophysical limits with the social foundations articulated in the Sustainable Development Goals and Kate Raworth’s “doughnut” model, highlighting how progress in health, education, and poverty reduction is now threatened by unsustainable practices. Yet sustainability frameworks often overlook politics, inequality, and public legitimacy. Growing social fragmentation, rising inequality, and populist backlash weaken support for sustainability action. Therefore, science-based frameworks must be complemented by approaches that embed justice, trust, and social licence if sustainability is to be durable and operational in policy and business practice.