The Sloan Digital Sky Survey is a multi-filter imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. Data Release 9 (DR9) offers the latest data from the Sloan Digital Sky Survey. Data Release 9 is the first release of the spectra from the SDSS-III's Baryon Oscillation Spectroscopic Survey (BOSS), which includes more than 800,000 spectra over 3,300 square degrees of sky, observed with the new 1,000-fiber BOSS spectrograph. Data Release 9 also includes all imaging and spectra from prior SDSS data releases, and provides corrected astrometry for the imaging from Data Release 8. Original acknowledgement for data: Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.