The synthesis and study of it novel thermosetting, blue photoluminescent, cyclolinear polycarbosilane (CLPCS.) are reported. This cyclolinear polycarbosilane, in which disilacyclobutane (DSCB) rings alternate with trans-stilbene units (i.e., [-{cyclo-Si(CH3)(CH2)(2)Si(CH3) -C6H4-CH=CH-C6H4-](n), (S-CLPCS), was prepared by via acyclic diene metathesis (ADMET) polymerization. The polymer showed excellent solubility in common organic solvents and blue photoemission with a high emission quantum yield (Phi approximate to 0.65). Spin-coated polymer films were thermally or photochemically cross-linked to yield tough, insoluble films, which showed no significant decrease in photoluminescence intensity relative to that of the initial polymer Film prior to cross-linking. The effect of the DSCB spacers on the processability and optical properties of the polymers was investigated by preparing it series of alkylene-spaced polycarbosilane analogues and model compounds.