We investigate the influence of ionic strength on the interaction between a cationic surfactant, hexadecyltrimethylammonium chloride (HTAC), and a water-soluble nonionic polymer, poly(ethylene oxide) (PEO). The formation of a charged PEO/HTAC complex is manifested by a maximum in the specific viscosity when a PEO solution is titrated with HTAC. The height of the viscosity maximum is diminished in the presence of salt because of the screening of electrostatic repulsions. Conductivity and differential refractometry measurements indicate that added salt (0.1 M KNO3) stabilizes the binding of HTAC micelles to the polymer. Static light scattering (SLS) studies in the absence of salt reveal the formation of multipolymer PEO-HTAC complexes at the maximum binding point, whereas in 0.1 M KNO3 predominantly unipolymer complexation occurs. Dynamic light scattering (DLS) analysis indicates, for the complex in water, a broad size distribution that corresponds to a widely polydisperse mixture of multichain clusters. In contrast, in 0.1 M KNO3 the size distribution of the complex is similar to that of the pure PEO. These changes in the structure of the PEO-HTAC complex appear to be driven through the screening of electrostatic repulsions between surfactant headgroups.