The results of the proposed experiments will directly inform clinicians who treat patients with osteoarthritis of the knee about how to maximize the benefits of acupuncture treatments. And because the experiments specifically asks the question of what is the relation between a patient's expectation of how a treatment will relieve their pain and the outcome of the treatment, the results will potentially inform care givers about all treatments for osteoarthritis and other chronic pain disorders. We hypothesize that acupuncture treatment will produce clinically significant analgesia as indicated by lowered sensory ratings of noxious stimuli and endogenous knee pain.