This study will present a technique for the retrieval of infrared land surface emissivity from high spectral resolution upwelling radiances. Results will be presented from aircraft flights of the Scanning High-resolution Interferometer Sounder (S-HIS) and the NPOESS Atmospheric Sounder Testbed - Interferometer (NAST-I). Case studies will be presented from ER-2 underflights of the Terra satellite at the Southern Great Plains ARM site in Oklahoma and over surface features during the NASA SAFARI experiment in South Africa.