We present a review of recent results from the Pierre Auger Observatory, including the measurement of the cosmic ray energy spectrum above 1018 eV, searches for anisotropy of the arrival directions, and studies of cosmic ray mass composition. The flux exhibits hardening at 4 × 1018 eV followed by suppression consistent with the GZK effect above 3 × 1019 eV. Correlation of cosmic ray air shower arrival directions with the distribution of the nearby extragalactic matter is observed at energies above 5.5×1019 eV. The observed longitudinal development of air showers suggests that the interaction cross-section increases with energy more rapidly than current models predict for proton primaries, perhaps due to a transition to heavier composition. No clear candidates for neutrinos and photons in the ultra-high energy cosmic ray flux have yet been found.