Amyloid fibrils are attractive targets for applications in biotechnology. These thin, nanoscale protein fibers are highly ordered structures that self-assemble from their component proteins or peptides. This chapter describes the use of several biophysical techniques to monitor the formation of amyloid fibrils including a common dye-binding assay, turbidity assay, and small-angle X-ray scattering. These techniques provide information about the assembly mechanism, the rate and reproducibility of assembly, as well as the size of species along the assembly pathway.