A growing body of evidence suggests that the symptoms of many fibromyalgia syndrome (FMS) sufferers might be the result of an imbalance in one of the major stress response systems, the autonomic nervous system. Thus respiratory sinus arrhythmia (RSA) biofeedback, which has shown promise in other conditions associated with an autonomic nervous system imbalance, could be effective in FMS. With the aid of sensors and computers, biofeedback involves modifying and/or learning how to control normally involuntary processes like blood pressure, heart rate and the autonomic nervous system through relaxation and breathing. The goal of this study is to test the effectiveness of a 10-session RSA biofeedback treatment for the symptoms of fibromyalgia. Forty patients receiving the RSA biofeedback treatment will be compared to 40 patients receiving another form of biofeedback thought to be minimally helpful (control group). Later, control group patients will also receive the RSA biofeedback treatment. We will study improvement in symptoms like pain, fatigue, sleep disturbance and depression in the RSA biofeedback group and compare these improvements to those in the control group. We will also assess whether these improvements persist over time and what if any changes in the autonomic nervous system result from the treatment.