We report observation of Bose-Einstein condensation (BEC) of a trapped, dilute gas of atomic hydrogen. The condensate and normal gas are studied by two-photon spectroscopy of the 1 S-2 S transition. Interactions among the atoms produce a shift of the resonance frequency proportional to density. The condensate is clearly distinguished by its large frequency shift. The peak condensate density is 4.8±1.1× 10 15 cm− 3, corresponding to a condensate population of 10 9 atoms. The BEC transition occurs at about T= 50 μ K and n= 1.8× 10 14 cm− 3.