Chain segmental motion and side-chain internal rotation of poly(1-naphthylmethyl acrylate) in dilute solution have been studied by employing the C-13 nuclear magnetic relaxation technique. Correlation times and diffusion constants were determined through dynamic modeling of the various modes of reorientation occurring in this polymer as a function of temperature and solvent viscosity. Local segmental motion and naphthyl internal rotation appear to follow Kramers’ theory, whereas the correlation time for the side-chain methylene internal motion scales as eta(0.55), instead of the first power dependence predicted by Kramers’ theory. The potential energy heights extracted from these measurements were found to be 11, 21, and 5.5 kJ mol(-1) for segmental motion, naphthyl restricted internal rotation, and methylene restricted internal rotation, respectively. Furthermore, on the basis of our data some general conclusions were drawn regarding solvent effects on the expected photophysical behavior of poly(1-naphthylalkyl acrylate)s.