Documented evidence shows that managers of units within the U.S. National Wilderness Preservation System are making decisions without reliable information on the amount, types, and distribution of recreation use occurring at these areas. There are clear legislative mandates and agency policies that direct managers to monitor trends in use and conditions in wilderness. This report is specifically designed as a convenient resource for wilderness managers and others who have the responsibility of monitoring and describing visitor use in wilderness. It is a comprehensive manual on estimation techniques and procedures that are essential to appropriately and accurately measure visitor use-related characteristics and conditions. Guidelines enable the manager to evaluate options and decide on a use estimation system that meets the needs of a specific area and set of circumstances. This handbook provides, in a single source, all relevant information on setting objectives, making decisions about what to monitor, developing a sampling plan, collecting the needed information, and computing basic statistics to provide input into management decisions. The user should have mathematical abilities at least through algebra; knowledge of statistics and calculus would be helpful.