The kinetics of smectic-phase formation in a siloxane copolymer, as compared with the crystallization of the relating homopolymer, was studied by the AVrami analysis of DSC data. A crossover from the diffusion-controlled kinetics (the Avrami exponent kappa similar to0.35) to the two-dimensional free-growth mode (kappa similar to1.5) with increasing temperature was detected. The influence of the annealing temperature on the sequence of mesophases, transition temperatures, and enthalpies of the polymers was also investigated.