The application of ester‐interchange reactions to the crystallization‐induced reorganization of random to block copolymers, which was demonstrated in the previous paper of this series, was followed quantitatively in this investigation. Structural changes based upon dyad compositions in copolyesters of terephthalic acid and 2‐methylsuccinic acid with ethylene glycol were determined by high‐resolution NMR. Sequence length distributions so calculated were related to the effects of copolymer composition, catalyst concentration, and reaction temperature on the rate of the ordering process and to the effect of structure on crystalline properties.