The book tells the unknown story of entrepreneurs who believed business could help create a more sustainable world. It challenges the received point of view that such green entrepreneurs are a recent phenomenon, and instead traces their origins much further back in the convictions of people committed to unusual lifestyles, in the zeal of radicals, and in the often unsuccessful efforts of visionaries to bring a new world into being long before the world was ready for it. This book looks at many such individuals in the United States, Europe, and elsewhere, and in industries as diverse as architecture, natural beauty, organic food, recycling, solar and wind energy, and sustainable finance. In each industry, the book explores the drivers of green entrepreneurship over time, how businesses were built, and the lessons to be learned. It is shown that it was only from the 1980s that green businesses were able to break out of marginal positions, yet the scaling of such businesses and the rise of corporate environmentalism raised new issues of legitimacy. The historical achievement of green entrepreneurs remains that through their willingness to be unconventional, they opened up new ways of thinking about sustainability, and have laid the foundations for the sustainable world of the future.