Poly (Arylene ethers) (PAEs) represent an important class of condensation polymers, which were used as a basis for obtaining a number of commercial thermoplasts possessing high performance characteristics. The main method used for the synthesis of PAEs is based on the polycondensation of alkali-metal bisphenolates with activated electrophilic monomers such as arylene dinitro compounds and arylene dihalide compounds. These processes belong to reactions of the nucleophilic aromatic polysubstitution type (SNAr2), involving etherification as the polymer forming process. This book presents and reviews research on aromatic polyethers.