With the new emphasis in land management agencies (particularly the USDA Forest Service) on ecosystem management, new attention is being paid to measurements of biological diversity (biodiversity). Forest managers faced with incorporating the maintenance of biodiversity into their analyses, plans, and decisions need reliable, quantitative biodiversity measures. Deciding which measures to use requires land managers to understand why biodiversity is valued, which components of diversity are of most value, and how to measure these components feasibly. In this paper, the values associated with biodiversity and the principal indices available to forest managers are reviewed. Attention is drawn to the differing emphases of biodiversity indices-species richness, heterogeneity, and evenness-and to how diese differences address different values. Potential applications for these indices in forest management plans-including ways to use habitat models to approximate biodiversity-are also discussed.