  The theory of neutrino oscillations explains changes in neutrino flavor,
count rates, and spectra from solar, atmospheric, accelerator, and reactor
neutrinos. These oscillations are characterized by three mixing angles and two
mass-squared differences. The solar mixing angle, {\theta}_12, and the
atmospheric mixing angle, {\theta}_23, have been well measured, but until
recently the neutrino mixing angle {\theta}_13 was not well known. The Daya Bay
experiment, located northeast of Hong Kong at the Guangdong Nuclear Power
Complex in China, has made a precise measurement of electron antineutrino
disappearance using six functionally-identical gadolinium-doped liquid
scintillator-based detectors at three sites with distances between 364 and 1900
meters from six reactor cores. This proceeding describes the Daya Bay updated
result, using 127 days of good run time collected between December 24, 2011 and
May 11, 2012. For the far site, the ratio of the observed number of events to
the expected number of events assuming no neutrino oscillation is 0.944 +/-
0.007(stat) +/- 0.003(syst). A fit for {\theta}_13 in the three-neutrino
framework yields sin^2 2{\theta}_13 = 0.089 +/- 0.010(stat) +/- 0.005(syst).
