Stratospheric aerosol properties, measurement techniques, and long-term data sets are reviewed in the context of the modeling of aerosol characteristics at CO2 laser wavelengths. The techniques for modeling infrared scattering characteristics, both from in situ particle size distribution measurements and from remote optical measurements at other wavelengths, are summarized, and the problems asociated with this modeling are discussed. Calculations based on measured size distributions show the backscatter coefficient at wavelength 10.6 μm, β10.6, to vary by a factor of the order of 100 between background and immediate postvolcanic conditions. The calculated value may also be quite dependent upon the scheme used to interpolate the number concentration between the measured particle radii. The ratio of backscattering at 10.6 μm to that at 0.694 μm, β10.6/β0.69, was found to vary by a factor of 5 for the same range of particle size distributions. A description is given of the rather limited amount of modeling at CO2 laser wavelengths and of data intercomparisons that have been published. A comparison of measured backscattering coefficient at 10.6 μm with those modeled from shorter wavelengths shows agreement within a factor of 2 or better. Areas of disagreement and uncertainity are identified together with the requirements for improving our knowledge of CO2 laser backscattering from stratopsheric aerosols. ¿American Geophysical Union 1991