Developed countries report that they mobilised $35 billion in international climate finance for developing countries through the “fast-start finance” period from 2010 through 2012. This study examines the reported contribution in detail, revealing lessons for mobilising and targeting climate finance over the coming decade.EDITOR'S NOTE: The report and data set have been revised to correct a currency conversion error that appeared in the original version, and to include data that were not available at the time the original version was published.