Impact measurement and management (IMM) has become a cornerstone of effective impact investing, moving beyond a basic reporting requirement to a strategic imperative. Recent research from the Global Impact Investing Network (GIIN) illustrates this shift, showing that organizations now dedicate an average of 12% of their total budget — and one-fourth of their staff time — to IMM. Integrating IMM into core investment processes is increasingly standard practice, with 81% of investors giving significant attention to impact during due diligence and 77% during investment screening. As the field matures, investors are evolving from basic metrics to more sophisticated measurement approaches, although challenges persist around data collection, metrics, and comparability.