Christiansen filters (CFs) are scattering filters composed of two materials with dispersion curves (for refractive index) that intersect at one wavelength. These filters have been fabricated with solid host matrices by mixing finely ground optical glass powders with pellets of optical grade resins and injection molding the combination into planar filters of various sizes. These filters transmit unscattered light of the intersection wavelength and incoherently scatter light of other wavelengths. Unlike filters based on optical interference, the transmitted wavelength does not depend on the angle of incidence on the filter. This paper will review the concept of CFs, describe fabrication procedures for composite materials, and display the spectral transmission measurements of the most promising filters.