A general method for the preparation of poly(aryl ether) alternating copolymers containing pendent cyano groups has been developed. We found that the activated aryl fluorides in 2-chloro-7-fluorobenzonitrile are selectively displaced by phenoxides to yield 3-chloro-2-cyanophenyl ethers as the exclusive products. Utilizing this selectivity, several new, high molecular weight, soluble poly(aryl ether amide) and poly(aryl ether ketone) alternating copolymers containing pendent cyano groups were prepared. The T(g)s of the copolymers ranged from 160 to 262 degrees C. The dielectric constants of the copolymers were characterized as a function of percent relative humidity. All of the copolymers were processable from solution to yield transparent, flexible films. At elevated temperatures the cyano groups undergo crosslinking reactions yielding films with high solvent resistance.