The importance of montane regions for biological diversity is well known. We also know that mountains contain a great deal of cultural diversity, despite the relatively small number of people living in mountains compared to other regions. What has been less explored is the interrelationship between mountains, biological diversity, and cultural diversity. The study of biocultural diversity involves a search for patterns across landscapes. As an inherently spatial phenomenon, biocultural diversity can readily be explored through the use of Geographical Information Systems (GIS). Our research has resulted in the development of a global database and map noting the linkage between high linguistic diversity and high plant diversity in montane regions throughout the world. In the present paper we focus mainly on the island of New Guinea to illustrate how important mountains are for biocultural diversity. The implications of this research for identifying areas in need of conservation and development strategies aimed at both biological and cultural diversity are briefly discussed.