Admixing polyelectrolyte to surfactant solutions will render their self-assembly behavior substantially more complex. While surfactants as a function of concentration typically show just one critical micelle concentration (cmc), above which micelles are formed, for surfactant/ polyelectrolyte mixtures several characteristic concentrations can be discerned. Depending on the strength of interaction (which will be most pronounced for oppositely charged surfactant and polyelectro- lyte) additional effects will be seen at concentrations below the cmc. Typically, different regions can be identified as a function of surfactant concentration Cs: