Excerpts from the Executive Summary: The U.S. Department of Agriculture (USDA) published its first version of Quantifying Greenhouse Gas Fluxes in Agriculture and Forestry: Methods for Entity-Scale Inventory in 2014, as directed by Section 2709 of the Food, Conservation, and Energy Act of 2008. In this updated version, USDA has revised the report to reflect the latest science‐based methods for estimating greenhouse gas (GHG) emissions and removals from agricultural and forestry activities. This report has several important purposes, including the following: • Enables landowners and others to estimate entity-scale GHG fluxes and impacts (including fluxes associated with different management practices) using the most accurate science-based methods currently available. • Allows USDA to estimate GHG fluxes from current and future conservation programs and practices and assess the performance of conservation and renewable energy programs using the most accurate science-based methods currently available given agency objectives and available resources. Note that the intensity metrics of GHGs (i.e., emissions per production unit) are not explicitly addressed in this guidance. • Provides a basis for updating USDA’s GHG flux estimation tools, including COMET-Planner and COMET-Farm (see box 1-2). • Informs GHG estimates for other programs. For example, this report may inform emerging methods that underlie voluntary GHG registries, facilitate regional GHG markets, and provide technical inputs for future GHG reporting programs. This report was developed by authors that have expertise in GHG accounting specific to agriculture and forestry. The authors were chosen based on their experience with GHG inventories and accounting methodologies and their professional research experience.