This report, Guidance on Organizational Life Cycle Assessment, is a milestone in measuring and improving environmental impacts and efficient use of resources at the organization level. It goes beyond assessing individual products, as has been done for many years, to encompassing an organization—public or private, big or small—as a whole. The report provides guidance to organizations on understanding, quantifying and communicating the environmental footprint of their activities and those of their value chain, thus providing them with a robust basis for sustainability decision-making. Organizational life cycle assessment (O-LCA) empowers organizations to envision their sustainability strategy, steer the design of their products, and improve their processes. It enables them to play a role in supporting the shift to sustainable consumption and production patterns, and the transition to a low-carbon, resource-efficient and inclusive Green Economy. This guidance document features 11 case studies of leading organizations that work beyond improving specific processes and products by progressively considering their whole value chains. In doing so, they have shown that life cycle assessment is an effective instrument for organizations, providing them with a sound scientific basis to underpin decisions towards sustainable consumption and production. The pioneers showcased are already reaping economic and other benefits of the life-cycle approach applied at the organizational level, for example through increased productivity and profitability by focusing their sustainability strategy where they can maximize positive change, identifying the most important potential partners within their value chains, and by communicating material and meaningful sustainability information to their stakeholders.