Polydi(3,4-dihydro-2H-pyran-2-methyl) esters of oxalic, adipic, and phthalic acids were prepared at different temperatures in the presence of different cationic initiators, namely, the boron trifluoride/diethyl ether complex system, anhydrous ferric chloride, and p-toluene sulfonic acid. The obtained polymers were hydrolyzed under basic conditions, and the polydispersity indices of these polymers were determined before and after hydrolysis. The results are discussed to shed some light on the ability to use this analysis to investigate the precise structure of the obtained polymers and to predict the ability of these polymers to form ladder or semiladder polymers. Characteristics of such polymers were dependent, to some extent, on the type of crosslinks and the cationic initiators used for polymerization as well as the reaction temperature. It seems possible to optimize the conditions leading to formation of ladder or semiladder polydi(3,4-dihydro-2H-pyran-2-methyl) esters of oxalic acid and adipic acid, respectively. The ladder structure was confirmed through determination of the polydispersity index before and after hydrolysis of the polymer formed at different temperatures and through computer-aided molecular modeling.