This proposal continues our investigations into polyelectrolyte-surfactant solutions which form films at the air-solution interface. We have found that solutions of mixed cat-anionic surfactants form films with a much wider range of polymers than cationic surfactants alone. The films grow from opaque solutions which contain large aggregates of the polymer with cat-anionic surfactants and although prior studies using SANS have identified the nanoscale structures in these solutions we would like to investigate the size and shape of larger scale aggregates in these solutions. Studies on film structure suggest polymers which interact strongly with the surfactants in solution result in cubic phases in the films, while weakly interacting polymers give lamellar phase films. We will use SESANS to study the particle size and shape for both classes of polymer in cat-anionic surfactant solutions.