Amyloid proteins cause a number of progressive, degenerative diseases. Among these is Alzheimer's disease (AD), the etiology of which is linked to the formation of neurotoxic assemblies by the amyloid beta-protein (Abeta). The clinical importance of AD has stimulated intense interest in the mechanisms of Abeta folding and self-assembly. Studying these phenomena in vitro requires the preparation of Abeta peptide stocks that are well defined and display reproducible biophysical and biological behaviors. Unfortunately, the propensity of Abeta to self-assemble has made this goal difficult. I discuss here a biphasic strategy for preparing Abeta for structural and functional studies. The strategy involves sodium hydroxide pretreatment of synthetic Abeta, followed by size fractionation procedures. This approach produces Abeta solutions that have been used successfully in a variety of in vitro and in vivo experimental systems.