We describe the Yale/San Juan Southern Proper Motion (SPM) Catalog 1.0, which provides positions, absolute proper motions, and photographic BV photometry for 58,880 objects at the South Galactic pole. The sky coverage of the SPM Catalog 1.0 is about 720 deg^2 in the magnitude range 5 < V < 18.5. About 55% of all catalog stars are randomly chosen, whereas the remainder contains numerous astrophysically interesting objects drawn from various lists and databases. The accuracy of positions and absolute proper motions is 40-150 mas and 3-8 mas yr^-1, respectively, depending on the star's magnitude. The high-end astrometric accuracy applies to the stars brighter than V = 15. A great deal of effort was put into correcting positions and proper motions for the magnitude-dependent systematic errors. The catalog can be used for Galactic structure studies and deep CCD-frame astrometric calibration and as a database for stars, galaxies, and other objects at the south Galactic pole. The catalog is supplemented by calibrated CCD BV photometry in selected 13' x 13' areas.