The proposed study aims to investigate experimentally anxiety sensitivity and physiologic sensations associated with anxiety using a paradigm combining hydrocortisone, caffeine, and a set of social stress challenges. Following informed consent, participants will be instructed to ingest either 400 milligrams of caffeine (an amount of caffeine roughly equivalent to that in two 8 oz. cups of brewed coffee from Starbucks), and 20 milligrams of hydrocortisone or two placebo capsules via stratified, random assignment. Physiologic and self-reported measures of stress and anxiety will be taken.