Previous chapters have explored the challenges and successes for Big Finance and Big Tech as they take on complex, Wicked Problems. The Deliberate Leadership framework set out in Chapter 3 provides ways to avoid unintentional harm and accelerate the good. This chapter examines key lessons about measuring the impact of activities on communities and the planet. These lessons are drawn from the team’s experiences in evaluation and grounded in the current thinking offered by, for example, the UN Sustainable Development Goals (SDGs), the Impact Management Project, and Social Value International. We also look at the importance of building impact measurement from the ground up by incorporating community feedback. We draw on content from cases analyzing the efforts of Hewlett Foundation, Fund for Shared Insight, and Concern Worldwide. Finally, Social Value International’s co-founder Jeremy Nicholls offers a new way to think, act, and scale social impact measurement to enhance equity, improve well-being, and increase environmental sustainability. Nicholls calls for social measurement to use accounting principles to ensure transparency, accountability, and social value. He highlights various actions that could be taken to build an impact accounting ecosystem similar to that which exists for financial accounting.