The World Bank, IUCN – The World Conservation Union, and The Nature Conservancy worked together to clarify the aims and uses of ecosystem economic valuation, focusing on the types of questions that valuation can answer, and the type of valuation that is best suited to each purpose. This document is the result of that co-operation. It does not seek to provide a detailed "how to" manual on economic valuation. This report aims instead to provide guidance on how economic valuation can be used to address specific, policy-relevant questions about nature conservation.