This report is an assessment of the condition of the natural resources of Isle Royale National Park (ISRO) and an evaluation of the threats and stressors that act on these resources. This assessment focuses on three broad resource groups: Lake Superior, inland waters, and terrestrial resources. It is based entirely on an in-depth review of scientific literature and agency reports, and on compilations, syntheses, and new analyses of existing data; no new field studies were conducted. It broadly describes ISRO and its natural resources, identifies stressors and threats to those resources, examines existing data about natural resource conditions, and makes recommendations for further study and management priorities where appropriate.