This document presents a series of technical guidelines by which land cover information is being extracted from Landsat Thematic Mapper data as part of the Upper Midwest Gap Analysis Program (UMGAP). The UMGAP represents a regionally coordinated implementation of the national Gap Analysis Program in the states of Michigan, Minnesota, and Wisconsin; the program is led by the U.S. Geological Survey, Environmental Management Technical Center. The protocol describes both the underlying philosophy and the operational details of the land cover classification activities being performed as part of UMGAP. Topics discussed include the hierarchical classification scheme, ground reference data acquisition, image stratification, and classification techniques. This discussion is primarily aimed at the image processing analysts involved in the UMGAP land cover mapping activities as well as others involved in similar projects. It is a "how-to" technical guide for a relatively narrow audience, namely those individuals responsible for the image processing aspects of UMGAP.