Mixed micelles formed by cetyl pyridinium chloride (CPC), Tween-40, and Brij-56 mixed in different proportions in an aqueous medium have been physicochemically studied in detail using tensiometric, conductometric, and fluorimetric techniques. The critical micellar concentration (CMC), free energies of micellization and interfacial adsorption, counterion binding, micellar aggregation number, and micellar polarity have been determined. To understand the CMC, composition, mutual synergism, and component activity coefficients of the mixed micelles, the theories and equations of Clint, Motomura, Rubingh, Rubingh and Holland, and Sarmoria, Puvvada, and Blankschtein have been used. Such studies on binary and ternary combinations are limited.