This paper describes the synthesis of side-chain liquid crystalline polymers and block copolymers by Living anionic polymerization and their thermotropic phase behavior. The polymers were successfully prepared with a narrow distribution of molecular weight. The thermotropic transition behavior between crystal, smectic A, and isotropic phases was examined with a function of the molecular weight. Living anionic polymerization also allowed the preparation of well-defined block copolymers with amorphous polystyrene. In these block copolymers, microphase separation due to liquid crystalline and amorphous blocks was observed by electron microscopy and small-angle X-ray methods. Effects of the microphase separation were also examined on the thermotropic phase behavior and structure.