The appraisal of mineral resources of the Challis National Forest, Idaho, by the U.S. Bureau of Mines was made so that the mineral resources of the forest could be appropriately considered in land use planning. Information from this study is intended to help the U.S. Forest Service to incorporate mineral resource data into forest plans. This study was done in conjunction with the U.S. Geological Survey, which released a companion report on the geology and mineral potential of the Challis National Forest in 1989. Mineral development activity in and near the Challis National Forest has been of great economic significance to Idaho and the United States. Since the 1860's, mines within the forest have produced mineral commodities worth more than $590 million at current (1989) commodity prices. Identified mineral resources have a gross value of about $2 billion at current prices and include eight strategic or critical minerals. This U.S. Bureau of Mines study identified and described 723 active and inactive mineral properties within the forest. Mineral properties with identified resources were evaluated to determine their economic significance, and an assessment was made of the feasibility of mineral development. Of the 2,516,191 acres in the Challis National Forest, about 390,000 acres were classified as having mining development interest. Commercially important mineral production, mainly of molybdenum, gold, and silver from the Challis National Forest, is likely for the foreseeable future.