To determine whether more than one subpopulation exists of patients with the diagnosis of Interstitial Cystitis (IC) based on sensory testing and to determine if subjects with IC have normal counterirritation-related modulatory systems. Previous studies by the PI suggest that two populations of subjects are present in the IC population but a larger number of subjects with IC would need to be tested in order to determine if this were indeed true. Other studies have demonstrated that counterirritation-related effects are absent in several chronic pain populations including fibromyalgia and chronic headaches. Identification of a subset of IC patients or the identification of a failure of counterirritation-related effects may predict responses to therapeutic interventions.