Monitoring progress towards meeting the Paris Agreement requires improving the tracking and measurement of public climate expenditure, investment, and revenues. This OECD working paper was prepared as part of the joint OECD-European Commission project on “Financing Climate Action in Regions and Cities”. It presents a pilot methodology for tracking, measuring, and comparing subnational government climate-significant expenditure and investment in OECD and EU countries based on National Accounts data. It also includes an analysis of the data collected, which is available in the new OECD Subnational Government Climate Finance database, and a stocktake of existing climate finance tracking initiatives. On the revenue side, the paper presents an analysis of climate-related public revenue sources available to subnational governments in OECD and EU countries, the results of which are available in the new online Compendium of Financial Instruments that Support Subnational Climate Action.