The investigators propose a three-site, RCT conducted at the Atlanta (lead site), Birmingham and Richmond VA's to establish non-inferiority of pelvic floor muscle exercise-based behavioral therapy compared to drug therapy for OAB symptoms in adults with PD. Groups will be stratified by OAB symptom severity, PD motor symptom severity, gender, and site. The investigators will randomize 90 participants in order to complete the study in 80 participants, assuming 85% power and a non-inferiority margin for the OAB symptom score of 15% at 12-weeks. The primary outcome measure will be urinary symptom severity as measured by the International Consultation on Incontinence Questionnaire (ICIQ)-OAB symptom score collected at 3 time points during the study: baseline, 6 weeks, and 12 weeks. The investigators' benchmark for successful treatment will be a 2 point reduction in the ICIQ-OAB symptom score, which corresponds with perceived benefit in preliminary studies of behavioral therapy treatment for OAB symptoms in PD. To evaluate the primary efficacy outcome, the investigators will utilize a random effects mixed model and adjust for baseline OAB symptom score severity. Additionally, in order to better understand central control mechanisms of bladder function, the investigators will determine if domain-specific cognitive function impacts the response to exercise-based behavioral therapy or drug therapy for urinary symptoms. At baseline and 12 weeks, randomized participants will undergo a brief neuropsychological battery. Understanding how domain-specific cognitive function impacts response to treatment may inform new targets for rehabilitation therapy.