This book provides readers with a basic understanding of sustainable finance and impact investing including history, definitions of impact, current trends and drivers, future challenges, and an overview of the key players in the global impact ecosystem. The term impact investing first appeared in 2008. Today the most commonly used definition is investing made with the intention to generate positive, measurable social and environmental impact alongside a financial return. A wide range of individual and institutional investors that have already entered the impact investment marketplace and continued growing enthusiasm can be expected given that feedback from investors indicated that portfolio performance has generally met or exceed their expectations for both social and environmental impact and financial return. Established companies have been compelled to respond to calls by institutional investors to incorporate responsible environmental, social, and governance initiatives into their business models as a condition to continued support in public capital markets. Other companies seeking to demonstrate to impact investors their commitment to environmental and social responsibility have opted for emerging forms of legal entities, so-called social enterprises, which explicitly incorporate sustainability and multi-stakeholder interests into their governance and reporting frameworks. This book provides readers with a basic understanding of sustainable finance and impact investing including history, definitions of impact, current trends and drivers, future challenges, and an overview of the key players in the global impact ecosystem. The book also describes impact investment structures and instruments, social enterprises, and impact measurement and reporting.