We prepared a polymer containing pendant norbornadiene (NBD) moieties,P(MMA0.43-co-GMA0.57-PNCA),and measured absorbance and refractive index spectra before and after photoisomerization of norbornadiene moieties. Large photoinduced refractive index changes of∼0.01were obtained at 632.8 nm, the region far from the absorption band. A quantum yield of 0.50 was obtained for the photoisomerization of NBD moieties in this polymer. These values are sufficient to make efficient channel waveguides by photoisomerization. ©1997 American Institute of Physics.