The interactions of surfactants sodium dodecyl sulfate (SDS), trimethyltetradecylammonium bromide (TTAB), and Triton X-100 with amphiphilic copolymers of acrylamide and dimethyldodecyl(2-acrylamidoethyl)ammonium bromide(DAMAB) have been investigated in aqueous solutions. The rheological properties of a copolymer/surfactant system are affected by both the microstructure of the copolymer and the nature of the surfactant. Addition of the nonionic surfactant, Triton X-100, resulted in a large increase in the reduced viscosity for the microblocky copolymers with 5 mol % DAMAB, while a random copolymer with the same composition exhibited a collapsed conformation in the presence of the cationic surfactant, TTAB. A strong viscosity enhancement was observed when SDS was added to the solution of a copolymer containing 0.32 mol % DAMAB. Evidence of mixed micelles formed by surfactant molecules and the hydrophobic groups of the copolymers was obtained utilizing surface tension, pyrene probe fluorescence, and viscometry.