The Cross-Track Infrared Sounder (CrIS) is NOAA's first operational hyperspectral sounder, flying on the NPP/JPSS platforms. It replaces the HIRS multi-channel radiometer that has been flying for decades. CrIS is a Fourier-transform spectrometer built by ITT, originally under the NPOESS program. We review here the pre-flight calibration of the CrIS sensor with an emphasis on spectral calibration. Several unique features of CrIS (relative to EOS/AIRS and METOP/IASI) will be discussed in context of their their impact on performance and calibration accuracy. We will also review in-orbit calibration/validation procedures and discuss aspects of the CrIS radiance record important for NWP radiance assimilation customers.