Many countries and regions face unprecedented social and environmental crises and disruptive events whose impact can no longer be ignored. Sustainable entrepreneurs offer new solutions to these problems that involve replacing the current linear economies by circular systems. Sustainable entrepreneurs generate new sustainable products, services, and production processes, with new sustainable business models that simultaneously balance ecological, social and economic goals, which result in sustainable welfare for current and for future generations. The DeGruyter Handbook of Sustainable Entrepreneurship Research studies the causes and consequences of sustainable entrepreneurship, the new standard of doing business and designing public policy, as reflected in the growth of sustainable entrepreneurship start-up ventures and the increasing integration of sustainability in small- and medium-sized enterprises as well as in incumbent corporations. It explores five main themes, each presenting state-of-the-art thinking: foundations, leadership, innovation, business models, performance and impact. Each section consists of four chapters that, taken together, offer in-depth perspectives, take stock of current situations and propose new avenues for future research. The handbook offers a coherent and systemic perspective for sustainable start-ups and for incumbent firms and governments aiming for transitions. It will also be of interest to scholars and postgraduate students interested in sustainable entrepreneurship.