Impact investing provides financial and non-financial resources to enterprises and investment funds with the goal to generate measurable social and/or environmental impact alongside a financial return. This special issue employs a business ethics lens to impact investing. The introductory essay clarifies six core terms that are frequently discussed to characterize impact investing and sets out a research agenda how business ethics scholars can help address and foster impact investing. The collection of eight papers addresses topics as varied as the inclusion of vulnerable stakeholders to address structural inequalities, the meaning of materiality, agency theory applied to impact-linked incentives, blended financial transactions, value incorporation in charitable foundations, identity tensions in faith-based investments, the ethical dilemma of social entrepreneurs pitching to commercial investors, and sense making of investors in renewable energy. Our goal is to inspire rigorous academic research on impact investing to build a knowledge base and to contribute to practice.