Fens are common wetlands in the Beartooth Mountains on the Shoshone National Forest, Clarks Fork Ranger District, in Park County, Wyoming. Fens harbor plant species found in no other habitats, and some rare plants occurring in Beartooth fens are found nowhere else in Wyoming. This report summarizes the studies on Beartooth fens from 1962 to 2009, which have contributed to current knowledge of rare plant distributions and biodiversity conservation. The study area is the Wyoming portion of the Beartooth Mountains in the Middle Rocky Mountains. Here, we profile 18 fens that occur over the range of elevations, settings, geomorphic landforms, and vegetation. The wetland flora from these 18 fens is composed of 58 families, 156 genera, and 336 vascular plant species—more than 10 percent of the known Wyoming flora. We discuss 32 rare vascular plant species and 1 bryophyte species associated with Beartooth fens and their State and regional significance. Protection and management of Beartooth fens are addressed in guidance documents prepared by the U.S. Forest Service Groundwater Program, regional peatland and sensitive species policies, and the Shoshone National Forest Management Plan. Information compiled in this report increases understanding of Beartooth fens, provides a basis for future research and comparisons with mountain fens elsewhere in Wyoming and the Rocky Mountains, and contributes to conservation of fen resources and services.