Phase diagrams for a series of self-assembled, stoichiometric poly [(acrylate)-co-acrylamide]-cetyltrimethylammonium (PAAm-CTA(+)) complexes in aqueous environments have been established using small-angle X-ray scattering (SAXS). Space groups and unit cell dimensions for each observed structure were measured as a function of salt type, ionic strength, polyelectrolyte charge density, and applied osmotic pressure. As osmotic pressure and charge density were increased, a phase sequence of Pm3n cubic <----> hexagonally close-packed cylinders (hcpc) <----> lamellar was observed over an osmotic pressure range of 0-1000 atm. This progression of structures was accompanied by a concomitant reduction in the Bragg spacings within each phase, and the osmotic pressure dependence of these spacings indicated the presence of exponential forces between surfactant assemblies. Typical unit cell sizes were on the order of 100-150 A for the cubic phase, 45-60 Angstrom for the hexagonal phase, and 25-35 Angstrom for the lamellar phase. Bragg spacings were also found to increase as ionic strength increased for each salt type studied, indicating that counterion release is a major driving force in the assembly of polyelectrolyte-surfactant complexes. At 1 M ionic strength, the complexes tended to dissociate into less well-ordered structures, presumably due to their becoming nonstoichiometric.