The Extragalactic First Look Survey is composed of 4 square degrees of imaging with MIPS and IRAC centered at J1718+5930, with extensive ancillary data from ground-based optical and radio telescopes. As one of the first observations made with Spitzer after the completion of Science Verification at the end of 2003 November, the aim of this 67 hr survey was to characterize the extragalactic source populations observed with Spitzer down to sub-millijansky levels in the mid-infrared.