At the conclusion of a screening period, qualifying subjects with a negative urine drug screen and ethanol breath test will be admitted to an inpatient research unit. After a 24 hour observation period confirming that the subject is not undergoing opioid withdrawal, subjects will randomly receive either 30 mg oxycodone or matching placebo over two consecutive days in a double-blind fashion. The purpose of this oxycodone vs. placebo qualifying period is to select for subjects with a positive drug liking response and to orient subjects to the various scales. Only subjects with a positive response on the visual analog "Liking" scale of at least 20 points higher on active oxycodone vs. placebo will be eligible to continue in the double-blind 7-way crossover study. Fourteen subjects will be randomized to one of fourteen sequences.