Molecular motions in polyarylates synthesized from substituted bisphenols have been investigated by dynamic mechanical analysis. Substitution at the ring carbon atom results in a more pronounced enhancement in glass transition temperature (T-g) as compared to substitution at the bridge carbon atom. The enhancement in mono and disubstituted polyarylates is more consistent than that in the case of polycarbonates and polysulfones. The beta transition has been shown to result from defects in the polymer samples. The molecular motion responsible for the tau transition in polyarylates has been shown to be more localized than in the case of polycarbonates. Introduction of the phthalide ring in the isopropylidene unit of bisphenol-A molecule results in splitting of the tau transition peak into two. The results have been compared with those reported for other bisphenol-based polymers, viz. polycarbonates and polysulfones, and explained on the basis of the structural attributes of the polymers.