The nature of the distribution of ionic groups in cesium salts of ethylene-methacrylic acid and ethyleneacrylic acid copolymers containing 2.1 to 6.3 mole percent acid was examined using small-angle and wide-angle x-ray scattering techniques. The low angle data containing a maximum characteristic of these materials was analyzed according to principles of small-angle scattering theory. The radial distribution functions for a typical salt and unionized copolymer were derived from the combined small and wide angle data. The results of these two approaches indicate the presence of ionic clusters of the order of 10-20 angstroms in size. There is evidence that these clusters are of spherical geometry. The low angle maximum is interpreted as an interference resulting from short-range ordering of ionic groups around ionic clusters. The crystalline nature of the salts and acid copolymers was examined by several techniques. The crystallinity level of annealed materials is essentially unaffected by ionization, while a strong dependence on acid content is observed and indicates the exclusion of carboxylic groups from the crystal structure. The effect of ionization is evident in crystallization behavior, crystallite size and lamella order.