The binding of sodium alkyl sulfates (C-8-C-16) to a copolymer of N-(vinylacryloyl)pyrrolidine and the covalently bonded chromophore 4-vinylpyridine dicyanomethylide has been studied by measuring the wavelength shift of the chromophore band at 390 nm. For the system sodium dodecyl sulfate and this polymer, the spectroscopic data have been complemented with electromotive force (emf) and isothermal titration calorimetry (ITC). From the combined emf and ITC data the critical concentrations associated with the binding process have been determined. Measurement of the extent of counterion binding indicates that the bound surfactant exists in the form of micellar type aggregates, and the spectral data indicate that initially these aggregates preferentially bind to the chromophore on the polymer.