The interactions and structure of complexes formed between bovine serum albumin (BSA) and the anionic surfactant sodium dodecyl sulfate has been investigated by spectroscopic probe techniques. Steady state and time-resolved fluorescence, electron spin resonance, and deuterium NMR spectroscopy have been employed as a multitechnique approach to investigate the structures which occur along the protein-surfactant isotherm. Three models of the protein-surfactant complex are considered. The results of the multitechnique approach are consistent with a structure which is predominantly of the "necklace and bead" type in which the unfolded protein wraps around surfactant micelles.