Abstract: Most quantitative methods for identifying conservation‐priority areas require more detailed knowledge about the extent and distribution of biodiversity than is currently available. Accelerated and irreversible losses of biodiversity call for the development of alternative methods to identify priority sites for biodiversity inventory and protection. We focused on the state of Arunachal Pradesh, a biodiversity‐rich region in northeast India. We used a geographic information system and spatially explicit modeling to examine the correlation of land‐cover and land‐use patterns with biogeophysical characteristics and to project future patterns of land‐use change. In 1988, 70% of Arunachal Pradesh was covered by forest. We project that 50% of the state's 1988 forest will be lost by 2021, based on anticipated growth of the human population and resulting resource use. Of the total simulated deforestation, 76% occurs in areas that have no legal state protection. We developed a map of threats to biodiversity that divides areas that were forested in 1988 into four categories: (1) susceptible to future deforestation and currently unprotected; (2) susceptible to future deforestation but currently within the protected‐area network; (3) not susceptible to future deforestation and protected; and (4) neither susceptible to future deforestation nor currently protected. We make the following recommendations based on our analyses. Areas in category 1 should be a high priority for biodiversity inventory and conservation action. Areas in category 2 should have rigid enforcement of protection. Areas in category 3 are locations of relatively low priority for enforcement. Areas in category 4 that have a high conservation potential are politically the easiest to include in the protected‐area network and should be protected before they become targets of future land‐use change. Reserve forests—forests managed by the state forest department for a variety of purposes, including selective logging for timber harvesting—are predominantly located in areas susceptible to land‐use change and are prime candidates for upgrading of protection status.