This essential book provides a comprehensive overview of early-stage impact investing, discussing best practices and equipping readers with the resources to make effective investments that achieve financial returns and societal or environmental benefits. The book's co-authors, who are academically trained and experienced impact investors, provide practical advice for purpose-driven startup investing. Each chapter delves into key topics such as setting and sourcing to an investment criteria, defining and measuring impact, structuring investments including setting valuation and determining investment terms, and portfolio management. The authors draw from a culmination of years of research, practice, and advising passionate founders of startups, emphasizing that impact investing will only continue to evolve as the field enters the mainstream. This book closes with a look forward to both the challenges and opportunities involved in impact investing. Students and scholars focusing on entrepreneurship, innovation, and finance will find this book to be highly beneficial. Additionally, it is useful for investors that are new to early stage impact investing, as well as seasoned investors seeking to move into early stage impact investing.