This document introduces MSCI's ESG Sustainable Impact Metrics and taxonomy for classifying companies' products and services according to their contribution to addressing major social and environmental challenges. The taxonomy focuses corporate activities into 5 themes: Basic Needs, Empowerment, Climate Change, Natural Capital, and Sustainable Impact Solutions. It also provides a framework for selecting companies with meaningful positive impacts and minimizing exposure to those with potential negative impacts. The document illustrates how the MSCI ACWI Sustainable Impact Index estimates over $500 billion in annual revenues derived from sustainable impact themes.