A test system and set of procedures have been developed to fully test and calibrate the Atmospheric Infrared Sounder (AIRS), a facility instrument on NASA's EOS PM platform. The system has been used to test and calibrate, under simulated space conditions, the spatial, spectral, radiometric and polarization characteristics of AIRS for each of its 2378 spectral bands covering the IR range from 3.7 and 15.4 micrometer. Unique challenges included spectral line shape and out of band response characterizations over 3 decades of the response function, accurate radiometric response calibration for IR source brightness temperatures from 195 to 357 K, spectral channel center and width determinations to 3 ppm of wavelength, spatial co-registration determination of the 2378 bands to 0.002 degrees and polarization response determination over all bands. Measured sensitivity, spectral response and polarization response for the AIRS instrument met or bettered requirements. The test systems developed to meet these objectives are described and the procedures and summary results of testing are presented.