Abstract The relationships between biological and cultural diversity are drawing increasing attention from scholars. Analyses of these relationships are beginning to crystallize around the concept of biocultural diversity, the total variety exhibited by the world's natural and cultural systems. Here, we present the first global measure of biocultural diversity, using a country-level index. The index is calculated using three methods: an unadjusted richness measure, one adjusted for land area, and one adjusted for the size of the human population. The adjusted measures are derived from the differences between observed and expected diversity values. Expected diversity was calculated using the species–area relationship. The index identifies three areas of exceptional biocultural diversity: the Amazon Basin, Central Africa, and Indomalaysia/Melanesia.