The Radioimmunoassay (RIA) Laboratory at Boise State University functions under the direction of Dr. Alfred Dufty. It is used to measure circulating levels of steroid hormones (e.g., testosterone, estradiol, corticosterone) in blood plasma. The protocol involves initial extraction of hormones from the blood and separation of individual hormones by column chromatography. The RIA itself involves the use of tritium-labeled (hot) hormone to compete with the unlabeled (cold) hormone for binding sites on a hormone-specific antibody. A scintillation counter measures the ratio of hot:cold hormone attached to the antibody in the sample, and a determination is made based on a comparison with known standards. Dr. Dufty presently uses the technique to investigate the physiological mechanism underlying avian responses to handling stress, dominance relationships, and changes in sex steroid hormones during the breeding season. Both graduate and undergraduate students have learned the RIA technique, and the skills involved are transferable to many other laboratory situations. Although Dr. Dufty’s personal research focuses on birds, investigations involving other taxa also are welcome.