The Third Data Release of the Sloan Digital Sky Survey

This paper describes the Third Data Release of the Sloan Digital Sky Survey (SDSS). This release, containing data taken up through 2003 June, includes imaging data in five bands over 5282 deg², photometric and astrometric catalogs of the 141 million objects detected in these imaging data, and spectra of 528,640 objects selected over 4188 deg². The pipelines analyzing both images and spectroscopy are unchanged from those used in our Second Data Release.