This guide to practical, science-based approach to national biodiversity assessment and prioritisation has been produced by the South African National Biodiversity Institute (SANBI) and the UNEP World Conservation Monitoring Centre. The approach is based on the principles of Systematic Conservation Planning and is augmented by 10 operating principles. It sets out a practical, science-based approach to spatial biodiversity assessment and prioritisation and forms an excellent starting point to inform national spatial planning exercises, including detailed advice for low resource situations.