Colloidal, "quantum-dot" semiconductormaterials, as exemplified by the sharp-cut yellow-red filter glasses which contain small (less than 100 A diameter) crystallites of cadmium sulfide and/or cadmium selenide, are of current interest because of the large near-resonant third-order nonlinear optical response they exhibit. Because these semiconductors are generally soluble only in inorganic media, such as silicate glasses, they have not been considered widely as candidates for inclusion in organic polymer waveguides. We report here the initial results of a continuing study in which very small colloidal particles of both cadmium sulfide and cadmium selenide (with crystallite diameters of typically 30-50 A) have been prepared by the reverse-micellar technique and then "capped" with a variety of organic reagents, using the methodology described several years ago by Brus and Steigerwa1d14. By varying the organic capping reagent, we find that we are able to produce significant variations in both the solublilty and the nonlinear optical response of the resulting composite materials. In particular, we find that the solubility of the particles in organic polymers such as PMMA and polycarbonate varies greatly with the nature of the capping reagent, with corresponding changes in the nonlinear refractive index of the composites. The feasibility of developing organic nonlinear optical waveguides based on this approach will be discussed.