A collection of cutting-edge methods for investigating G protein signaling from a variety of perspectives ranging from in vitro biochemistry to whole animal studies. Among the readily reproducible techniques presented are those for the purification of G proteins and effectors enzymes, assays of these purified G proteins and effector enzymes, and for the study of G proteins interactions with effectors in intact cells. Additional methods are provided for assaying G protein coupled receptor structure, function, and localization; for studying the physiological roles for endogenous G proteins; and for examining lipid and phosphate modifications of RGS proteins.