This book provides an approach to sustainable decision-making rooted in financial and economic literature. Financial economic techniques have the power to frame the discussion of sustainability to explain who, how, and why sustainability is a growing phenomenon in business and investing. Financial concepts in a sustainable framework provide a theoretical basis to approach research and business questions on sustainability. The framework provides for a better understanding of the different definitions of sustainability and the role those differences have on decisions that will lead to the future of sustainable business. A future which relies on growth driven by expanding its markets' reach (demographics), its innovation or creation of new products, and its capital structure (leverage). Third party certification and governmental regulation become the constraints on that growth as well as the proof of sustainable growth. Finally, the ability and methods for investors to support sustainable growth is addressed in a modern portfolio theory analysis.