A novel series of comb-like amphiphilic statistical copolymers were synthesized by polymerization of an amphiphilic macromonomer, 2-(acrylamido)-dodecanesulfonic acid (AMC(12)S), with 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS). The association behaviors of the polymers in NaCl aqueous solution were investigated by steady-state fluorescence measurements with pyrene as a polarity probe, quasielastic light scattering techniques (QELS), and a transmission electron micrograph (TEM). It was found that the series of polymers shows a strong tendency for interpolymer association, leading to the formation of multimolecular aggregates. The critical aggregation concentration (CAC) and the micropolarity of the polymer aggregates strongly depend on AMC(12)S mole fraction (X). An interesting feature of the polymers is that hydrodynamic sizes of the aggregates (R(h)) Continuously decrease with increasing X, and the increase extent of Rh with increasing polymer concentration (C) inclines to be smaller for higher X, suggesting that the polymer aggregates become a closed type progressively with increasing X.