A variety of polymers containing NLO-active chromophores covalently bound in the siloxane-linked backbones, [-R2Si(OSiR2)(n)O(NLO-chromophore)O-](n) (R = CH3 or CH3/C6H4) and [-R2Si(OSiR2)(n)-OR＇O(NLO-chromophore)O-](n) (R＇ = C6H4, C6H4C6H4), has been prepared. Their solubility in common organic solvents and high thermal stability impart ease of thin film preparation and poling at high temperatures. These polymers exhibit good second-harmonic generation susceptibilities, and the temporal stabilities of the SHC signals are dependent on the polymer backbone and the molecular structures of the NLO chromophores. A detailed analysis of their physical properties is reported.