Electrophoretic light scattering, dynamic light scattering, turbidity, and static light scattering were used to study complex formation between poly(dimethyldiallylammonium chloride) (PDMDAAC) and oppositely charged mixed micelles of Triton X-100 (TX100) and sodium dodecyl sulfate (SDS) in 0.4 M NaCl. Interpolymer complexes form with an increasing bulk weight ratio of PDMDAAC to TX100-SDS, W, at constant [TX100-SDS]. The turbidity, scattered light intensity, and apparent hydrodynamic radius of the complexes all reach maxima at W approximate to 0.09. This value of W corresponds to a net charge ratio of PDMDAAC to TX100-SDS of 1:1. Electrophoretic light scattering indicates that the electrophoretic mobility of the complexes changes from negative to positive with increasing W and is close to zero around W similar to 0.09. However, neither precipitation nor coacervation is observed, in contrast to typical polyelectrolyte-oppositely charged surfactant systems. The results support a model for the complex wherein only a fraction of the charged residues are associated with corresponding charges on the TX100-SDS mixed micelles.