We have prepared various polysilane copolymers that were functionalized with the nonlinear optical chromophore N-methyl-p-nitroaniline. The glass transition temperature of the polysilanes was adjusted to room temperature by copolymerization of methylphenyldichlorosilane and n-hexylmethyldichlorosilane. Asymmetric two-beam coupling was observed at 633 nm, and a gain coefficient of 18 cm(-1) was measured at an externally applied field of 48 V mu m(-1).