The MiniBooNE short-baseline neutrino experiment at Fermilab observes a significant excess of electron-like events. From 2.4E21 protons on target in neutrino and antineutrino mode, a total electron-neutrino charged-current quasi-elastic excess of 460.5 +- 99.0 events (4.7 sigma) is observed in the neutrino energy range from 200-1250 MeV. If interpreted in a standard two-neutrino oscillation model, the best oscillation fit to the excess has a probability of 21.1%, while the background-only fit has a chisquare probability of 6E-7 relative to the best fit. The MiniBooNE data are consistent in energy and magnitude with the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND), and the significance of the combined LSND and MiniBooNE excesses is 6 sigma. All of the major backgrounds are constrained by in-situ event measurements, so non-oscillation explanations would need to invoke new anomalous background processes.