 We chose to study drug and CBT for several reasons: 1 the scarcity of trials that manipulate medications along with CBT in FMS, 2 the prohibitive nature of adding an exercise treatment arm in a study that has both time and budgetary constraints, 3 the complexity in understanding the mechanism of actions of 3 different modes of intervention in one clinical trial, and 4 the desire to explore mechanisms in this program of research, in particular the potential effects of a biological intervention drug on what is traditionally considered a psychological outcome pain-related attributions and cognition and the potential effects of a psychological intervention CBT on what is traditionally considered a physiological outcome pain sensitivity. 