Side-chain Liquid-crystalline copolymers containing both a mesogenic (carbazolylmethylene)-aniline group as the electron donor and a mesogenic (4’-nitrobenzylidene)aniline group as the electron acceptor with alkylene spacers of different lengths were prepared. The thermal stabilization and the induction of the smectic phases were observed for the copolymers containing spacers with similar lengths. For example, the copolymer containing both a hexamethylene spacer in the carbazolyl group and a trimethylene spacer in the nitrophenyl group exhibited a smectic phase from 77 to 191 degrees C, though the smectic phase did not appear in both homopolymers. On the other hand, these tendencies were not seen for the copolymers with spacers of a large variation in the length, i.e., undecamethylene and ethylene spacers. Thus, it is revealed that the thermal stability and the induction of the smectic phases in the copolymers are influenced to a large extent by the degree of overlapping between the mesogenic side groups through the electron donor-acceptor interaction.