Poly(arylene ether)s containing phosphorus, sulfur, and heterocyclic pendant moieties were synthesized and their properties investigated. The preparation of monomers containing phosphorus as well as monomers derived from phenolphthalein were synthesized in high purity. These monomers were then successfully polymerized by a nucleophilic displacement reaction to prepare poly(arylene ether)s of both high and controlled molecular weight. The novel poly(arylene ether)s based on phenolphthalein had glass transition temperatures ranging from 265 to 312 °C. Furthermore, the modulus of these macromolecules was significantly higher than that of typical poly(arylene ether)s (e.g. bisphenol A based systems), probably as a result of enhanced intermolecular forces. Phenolphthalein in poly(arylene ether)s has been shown not only to improve the thermal and mechanical properties, but also it provides a pendant functional group for chemical modification of the polymer. As a result, a base polymer can be customized to a variety of new materials using derivatization techniques. The possibility of metal complexing in phenolphthalein poly(arylene ether)s was also investigated. A variety of reactive and non-reactive end-capped poly(arylene ether)s of controlled molecular weight were synthesized for use in reactive toughening modified epoxy and cyanate ester networks and these results are briefly summarized. Model studies using HPLC were also conducted to determine reaction kinetics in nucleophilic poly(arylene ether) formation. The results demonstrate that potassium carbonate mediated step polymerizations likely proceed with etherification of one of the phenolic groups, prior to difunctional coupling, which can achieve high molecular weight. The formation of cyclic oligomers in the step-growth polymerization of poly(arylene ether)s was also studied. / Ph. D.