Independent fiscal institutions (IFIs) serve to promote sound fiscal policy and sustainable public finances. Their numbers in the OECD have more than tripled in the past decade and continue to grow. Today IFIs are considered among the most important innovations in the emerging architecture of public financial management. The OECD has identified good practices for designing and operating effective IFIs through the OECD Recommendation on Principles for Independent Fiscal Institutions. The analysis presented in this paper draws on the OECD IFI database compiled from a first set of case studies of 18 OECD IFIs in Australia, Austria, Belgium, Canada, Denmark, Finland, France, Ireland, Italy, Korea, Mexico, Netherlands, Portugal, Slovak Republic, Spain, Sweden, United Kingdom and the United States.