This is part of three documents, where this is the full report. These documents describe the key findings, research methods, assessment results, and suggestions for future work resulting from the compilation of the Global Database of National GHG Inventory Capacity in Developing Countries. Principle to this research was the creation of two GHG inventory capacity indices, GHGI Capacity and GHGI Applied. The two indices can be used to assess the evolving capacity of developing countries to prepare national GHGIs under the United Nations Framework Convention on Climate Change (UNFCCC). GHGI Capacity represents the inherent capacity of countries, and is calculated by the sum of three weighted dimensions of nine (9) indicators. These dimensions are labeled as country context, institutional structure, and technical skills and knowledge of individuals. GHGI Applied represents the country’s capacity that was actually performed through submitted GHGIs. It can be measured by scoring seven (7) indicators of the quality of submitted GHGIs: Promptness, transparency, accuracy, completeness, time-series, recalculation and key category assessment, and uncertainty analysis. By assessing GHGI Capacity and GHGI Applied for 133 developing countries and across three (3) GHGI submissions, we can trace the evolution of GHGI capacity worldwide in an explicit and quantifiable manner. The assessment results can then inform where and in which dimensions of GHGI capacity additional improvements may be needed in a country to realize the UNFCCC reporting requirements, including under the Paris Agreement’s Enhanced Transparency Framework (ETF).