This General Technical Report (GTR) addresses monitoring strategies for terrestrial animals and habitats. It focuses on monitoring associated with National Forest Management Act planning and is intended to apply primarily to monitoring efforts that are broader than individual National Forests. Primary topics covered in the GTR are monitoring requirements; ongoing monitoring programs; key monitoring questions and measures; balancing three necessary and complementary forms of monitoring (targeted, cause-and-effect, and context); sampling design and statistical considerations; use of the data that result from monitoring; and organizational and operational considerations in the development and implementation of monitoring programs. The GTR concludes with a series of recommendations for the ongoing improvement of monitoring of terrestrial animals and their habitat.