The aggregation of a short-chain nonionic amphiphilic poly(p-phenylene) in aqueous micellar solutions of the nonionic surfactants C8E4, C12E6, or C(10)G(2) was studied. Cryo-transmission electron microscopy reveals the existence of fiberlike aggregates of mean length greater 200 nm and a diameter of ca. 6 nm surrounded by an excess of small surfactant micelles in these solutions. Static and dynamic light scattering were used to characterize the fiber aggregates in these complex liquid mixtures. The scattering data were analyzed by model-based and model-independent procedures, which yield the mean length L, the polydispersity k, and the radial aggregation number N-rad of the fiber aggregates. The dynamic behavior of the aggregates can be described by a model for polydisperse rigid rods, taking into account their translational and rotational diffusion.