This study is part of a broader evaluation of donor support to public financial management (PFM) reforms in developing countries. It brings together available quantitative evidence on the quality of PFM systems, to assess the factors that are associated with and may have determined cross-country differences and variations over time, with a particular focus on the impact of donor support to PFM reforms. The bulk of the analysis draws on data from Public Expenditure and Financial Accountability (PEFA) assessments in 100 countries, data on donor support to PFM reforms collected directly from some of the donor agencies most active in this area and a large dataset on other economic/social, political/institutional and aid-related variables identified as relevant from previous research.