The association behavior of random copolymers of sodium 2-(acrylamido-2-methylpropanesulfonate (AMPS) and dodecyl methacrylate (DMA) with its content (f(DMA)) varying from 1 to 15 mol % was investigated by fluorescence and quasielastic light scattering (QELS) techniques in 0.1 M NaCl aqueous solutions. The association behavior of the copolymers was found to depend strongly on f(DMA) When f(DMA) < 3 mol %, some polymer chains exist as unimers with a hydrodynamic radius (Rh) Of about 5 nm while some polymers form multipolymer aggregates with Rh approximate to 100 nm, arising from 'hydrophobic cross-linking" by the interpolymer association of dodecyl groups. When f(DMA) is increased to 9 mol %, interpolymer hydrophobe associations lead to the formation of a multipolymer micelle with Rh approximate to 10-13 nm. The aggregation number (N-agg) of dodecyl groups in a micelle core was estimated to be about 195. When f(DMA) is further increased to L5 mol %, Rh for the multipolymer micelle markedly increases to 70-180 nm, the size increasing with increasing polymer concentration, whereas N-agg,,, remains constant at about 158 independent of the polymer concentration. On the basis of the results from the fluorescence and QELS measurements, a unicore micelle model was proposed for the copolymer with f(DMA) = 9 mol %, and a bridged micelle model was proposed for the copolymer with f(DMA) = 15 mol %.