In the past several years significant attention has been given to the analysis of the properties and functions of lateral microdomains (rafts) in biological membranes. As described in the overview chapter of this book, as well as in the introductions to many of the other chapters, there are many fundamental un- swered questions concerning the composition, structure, dynamics, and even the very existence of these membrane rafts. Therefore, a variety of sophisticated techniques have been used to study intact cell membranes, as well as model s- tems composed of specific lipids and proteins thought to be in rafts. The analyses of biological membranes have provided detailed data on intact microdomains, and the complementary studies of model systems have given critical insights on the roles of specific lipid-lipid and lipid-protein interactions in raft formation and function. The chapters in this book provide detailed information on modern methods that are currently being employed to study lipid rafts.