Little is known about fens in Grand Teton National Park (GRTE) and John D. Rockefeller, Jr. Memorial Parkway (JODR). To better manage fen resources in GRTE and JODR, the National Park Service funded the Colorado Natural Heritage Program to create a map of potential fens within GRTE and JODR, visit potential fen polygons to verify their status as fens, and survey for rare fen-indicator plant species. Potential fens were mapped in the winter of 2022-23. The initial map of fens contained 906 potential fens covering 5,208 acres. Field sampling took place in the summer of 2023 and verified 41 fens and 28 peat-accumulating wetlands. Field sampling also confirmed that 48 polygons were not fens. The revised map contained 1,016 acres of confirmed or highly likely fens, which were concentrated at elevations below 2100 m in specific areas of the parks, including Lower Jackson Lake watershed and most of JODR. One hundred and twenty-seven populations of 23 rare fen-indicator plant species were observed either within or near confirmed fens. Rapid vegetation surveys were conducted in 38 confirmed fens. Most fens were characterized as rich fens, with some considered poor fens and no sites meeting the water chemistry and vegetation classification of extreme rich fen. GRTE and JODR fens are exceptional resources that support numerous rare species. Management plans for the park units should protect and avoid impacting these special habitats and their species so they remain intact into the future.