The inclusion and Co-60 gamma-ray-initiated polymerization of vinylic and acrylic monomers within the clathrate tunnels formed by tris(o-phenylenedioxy)cyclotriphosphazene is described. Methacrylonitrile, methacrylic acid, ethyl acrylate, butyl acrylate, hexyl acrylate, allyl methacrylate, vinyl acetate, and vinylanisole monomers were included by direct contact imbibition. Varying degrees of stereoregularity were obtained from the inclusion polymerization of the monomers listed above. For example, poly(methacrylonitrile) synthesized within the host adduct showed an enhanced isotactic microstructure. Another aspect of clathrate-mediated polymerization is that no radiation cross-linked material was obtained for polymers derived from the acrylates and methacrylonitrile, in contrast to the corresponding radiation-induced bulk polymerizations. The copolymer poly(vinyl acetate-co-methyl acrylate) was also prepared using the inclusion polymerization method.