The rise in reporting of sustainability performance goes hand-in-hand with stakeholders' demands for reliable and credible information from management. This chapter looks at the standards for sustainability reporting, the content, format, and distribution of reports, external disclosure of sustainability measures, verification, and internal and external sustainability auditing. The Ceres Principles were an attempt to standardize information and emphasized the importance of both internal and external evaluations of sustainability performance. Global Reporting Initiative (GRI) incorporates the active participation of corporations, NGOs, accountancy organizations, business associations, and other stakeholders from around the world. A growing community of impact investors, who deliberately invest for social and environmental impact, cannot fully evaluate impact investment with GRI. The National Community Investment Fund (NCIF) and the Impact Reporting and Investment Standards (IRIS) initiative managed by the Global Impact Investing Network (GUN), a US-based non-profit organization, have harmonized their respective metrics to increase impact investors' use of standardized social metrics.