A dedicated 3 Gel’ injector spnchrotron for the storage ring SPEAR has been constructed at the Stanford Synchrotron Radiation Laboratory. SSRL. and has become operational by November 1990. The injector consists of an If-gun. a 120 MeI- linear accelerator. a 3 Gel’ booster sgnchrotron and associated beam transport lines. General design features and special new developments for t.his injector are presented together with operational performance. an energy of 3 Ge\’ and an intensity which would allow to fill SPEAR to 100 ma in less than 5 minutes. The electron source is a 2.5 Me\’ rf-gun and after acceleration to 120 MeV in a linear accelerator the particles follou- a short beam transport line to the booster spnchrotron. The booster magnets are energized by a White circuit cycling at 10 Hz. After reaching the SPEAR injection energy the beam is kicked out of the booster into a beam transport line to SPEAR.