Drawing upon the results of a three year project at the World Conservation Monitoring Centre, this paper examines national investment in protected areas as a financial indicator for biodiversity conservation. An overview of the existing data on financial indicators and targets for biodiversity conservation is presented, including the recently completed global survey of government budgets for protected areas by the WCMC. The paper then discusses the methodological issues involved in standardizing data on investment in protected areas, the setting of target investment levels, and ways to improve the future collection of such information. The discussion is conducted within the framework of the upcoming national reports by the Parties to the Convention on Biological Diversity, and the specific objective of establishing financial indicators from the data included in the national reports.