Additional Study Information: This study is for adults with Overactive Bladder. The purpose of this registry is to collect information about patients who have Overactive Bladder (OAB) and who are receiving either mirabegron or another approved antimuscarinic medication (single drug). To collect this information, the study Sponsor has created a research registry. A registry is a kind of databasea way of collecting and keeping information. This registry is being set up is to identify how well treatment of OAB is working. The doctor and their staff will collect information about your health and will share this information with the sponsor and a company hired to do the research. Each person in the study will have his/her information collected for up to 12 months. Participants will be asked complete online questionnaires about their OAB.