This report, Current Challenges and Priorities for Greenhouse Gas Emission Factor Improvement in Select Asian Countries, focuses on a key initiative of the LEAD program, namely to improve GHG inventories and GHG accounting systems and practices. The national GHG inventories in Asia exhibit diversity in their methodological complexity, accuracy, and specificity to national circumstances. In addition, the majority of GHG inventory estimates rely on default emission factors provided by the Intergovernmental Panel on Climate Change (IPCC), as opposed to using country-specific emission factors (CSEFs) tailored to country conditions. The use of simplified representations of emission factors with default values that do not reflect in-country conditions is one of the main sources of uncertainty within national GHG inventories. Use of CSEFs instead of default values can reduce the level of uncertainty in national GHG inventories.