Technical Abstract: Assessment and monitoring are necessary to continuously adapt management to ensure it is meeting land management objectives. Ecologically based assessment and monitoring are required for sustainable land management because long-term sustainability depends on maintaining particular ecological processes. This paper reviews several relatively new concepts, including ecological resistance and resilience and ecological, management and economic thresholds. These concepts are required to use assessment and monitoring to increase sustainability. The paper concludes with a description of a system for combining short- and long-term monitoring as part of a cost-effective adaptive management program.