The potential and problems of using species diversity information, derived from the Southern African Bird Atlas Project (SABAP), are examined. Atlas data were analysed and the problem of uneven sampling effort was ameliorated through an application of an index of diversity. Maps of diversity for various suites of species are considered in relation to their implications for conservation planning. An approach to the identification of high-priority areas for conservation, based on an index of diversity, is described and called the Compatible Sets Approach. Birds in the grassland biome are used to illustrate the principles of the approach.