Monitoring is crucial for determining trends in plant and animal populations and their response to management. However, decisions about how much to invest in monitoring, and where, when and how to allocate monitoring effort, are complex. Poorly designed or under-resourced monitoring programs can fail to detect important changes in species abundance and/or distributions, leading to warning signs being missed or valuable conservation resources wasted. This project will further develop a computer simulation tool (SPOTR) for evaluating the performance of biodiversity monitoring programs. In collaboration with Parks Australia, the tool will assess existing monitoring programs in a selection of Australian Government national parks to compare the cost-effectiveness of alternative monitoring designs.