The molecular parameters responsible for the solution properties of poly(styrenesulfonate) ionomers in both a polar and a relatively nonpolar solvent have been studied. The second virial coefficients, apparent molecular weights, and diffusion coefficients have been measured by a combination of static and quasi-elastic light scattering techniques. Solution viscosities have also been measured. From this combination of scattering and rheological information, a more detailed description emerges of ionomer solution behavior over a range of solvent polarities, polymeric molecular weights and ionic contents, and concentrations.