  This presentation describes a measurement of the neutrino mixing parameter,
sin^2(2theta_13), from the Daya Bay Reactor Neutrino Experiment. Disappearance
of electron antineutrinos at a distance of ~2 km from a set of six reactors,
where the reactor flux is constrained by near detectors, has been clearly
observed. The result, based on the ratio of observed to expected rate of
antineutrinos, using 139 days of data taken between December 24, 2011 and May
11, 2012, is sin^2(2theta_13) = 0.089 +/- 0.010(stat.) +/- 0.005(syst.).
Improvements in sensitivity from inclusion of additional data, spectral
analysis, and improved calibration are expected in the future.
