Forest certification is widely seen as an important component of strategies for conserving the world"s forests. During the 1990s concern about the loss of biodiversity in logged forests was a key driver behind the emergence of forest certification. It was thought that by adhering to strict standards, production forests could help protecting biodiversity. Forest certification was introduced more than 15 years ago and since then more than 300 million hectares of forests have been certified under a variety of schemes. But does it work? Tropenbos International (TBI) now presents the results of a literature study evaluating the effects of forest certification on the biodiversity of temperate, boreal, and tropical forests. This publication addresses the effects of forest certification on biodiversity by discussing what biodiversity is, how it is measured, what sustainable forest management is, and by analyzing the available scientific literature on the effects of forest management activities and certification on biodiversity.