This report discusses the landscape of the U.K. social investment market, with a focus on impact investing; reviews the barriers to the growth of the market and potential solutions; and outlines a decision-making framework to help investors evaluate and implement social investments within a diversified investment portfolio. While this report is focused on the social investment market in the United Kingdom, investors outside of the United Kingdom may find it helpful to read this report to learn about the innovative impact investment opportunities available in the U.K. market and to understand the decision-making framework we propose, which could be helpful to investors in other markets.