Little is known about recent rates of carbon storage in montane peatlands, particularly in the western United States. Here we report on recent rates of carbon accumulation (past 50 to 100 years) in montane groundwater-fed peatlands (fens) of Yosemite National Park in central California, U.S.A. Peat cores were collected at three sites ranging in elevation from 2070 to 2500 m. Core sections were analyzed for bulk density, % organic carbon, and ²¹⁰Pb activities for dating purposes. Organic carbon densities ranged from 0.026 to 0.065 g C cm^-3. Mean vertical accretion rates estimated using ²¹⁰Pb over the 50-year period from ∼1960 to 2011 and the 100-year period from ∼1910 to 2011 were 0.28 (standard deviation = ±0.09) and 0.18 (±-0.04) cm yr^-1, respectively. Mean carbon accumulation rates over the 50- and 100-year periods were 95.4 (±25.4) and 74.7 (±17.2) g C m^-2 yr^-1, respectively. Such rates are similar to recent rates of carbon accumulation in rich fens in western Canada, but more studies are needed to definitively establish both the similarities and differences in peat formation between boreal and temperate montane fens.