Introduction: Good Practice Guidance for SDG Indicator 15.3.1 In the last decade, there have been a number of global/regional targets and initiatives to halt and reverse land degradation and restore degraded land. Starting in 2010, these include the CBD’s Aichi Biodiversity Targets, one of which aims to restore at least 15% of degraded ecosystems; the Bonn Challenge and its regional initiatives to restore more than 150 million hectares; and most recently the 2030 Agenda for Sustainable Development and the Sustainable Development Goals (SDGs). The SDGs provide a framework for countries to determine how best to improve the lives of their people now while ensuring that these improvements are sustained for future generations. The SDGs came into effect in January 2016 and are expected to guide social, economic, and environmental policy and investment over the next 15 years. SDG 15 promotes “Life on Land” and SDG target 15.3 states: ‘By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world.’ The United Nations Convention to Combat Desertification (UNCCD) is the custodian agency for SDG indicator 15.3.1 (“Proportion of land that is degraded over the total land area”) which was proposed by the Inter-Agency and Expert Group on SDG indicators (IAEG-SDGs) and adopted by the United Nations Statistical Commission (UNSC) in March 2017 to monitor progress towards achieving SDG target 15.3. The UNCCD and its key partner, the Food and Agriculture Organization of the United Nations (FAO), have convened an inter-agency advisory group to develop and refine the methodology and data options contained in this Good Practice Guidance (GPG) for SDG indicator 15.3.1. The group also includes the United Nations Framework Convention on Climate Change (UNFCCC), Convention on Biological Diversity (CBD), United Nations Environment (UNEP), and the United Nations Statistics Division (UNSD). SDG indicator 15.3.1 will be reported as a binary (i.e., degraded/not degraded) quantification based primarily, and to the largest extent possible, on comparable and standardized national official data sources. This GPG aims to assist countries in implementing the methodology for deriving SDG indicator 15.3.1 (“the indicator”) by calculating and assessing changes in i) land cover, ii) land productivity and iii) carbon stocks (“the sub-indicators”) in concert. The methodology is intended to be universal, allowing countries to select the most appropriate datasets for the sub-indicators and determine the most suitable pathway for deriving the indicator. This GPG also recognizes that any significant negative change in the sub-indicators pointing to land degradation is context-specific and to be determined by national authorities based on a convergence of evidence, i.e, complemented with other indicators, data, and information. This GPG describes the methods to process and interpret data from available sources that can be used to support countries in their assessment and quantification of land degradation. While it is difficult for a single indicator to fully capture the state or condition of the land, the sub-indicators are proxies to monitor the key factors and driving variables that reflect the capacity of the land to