Overactive bladder (OAB) is very prevalent and may be very bothersome. In this chapter, we describe the various definitions associated with this condition, its assessment and management. The definitions for lower urinary tract symptoms have been standardized by the International Continence Society. OAB is a symptomatic diagnosis after all other pathology has been excluded. Important assessments include a frequency volume chart and in some cases urodynamic studies. Here we describe the important parameters which should be sought from a frequency volume chart. In addition, the relationship to the urodynamic diagnosis provided by a cystometry study is explained. Thereafter we discuss the therapeutic options for OAB which include conservative measures, antimuscarinics, beta-3 agonists, intravesical botulinum toxin, neuromodulation, and surgery. The various management options including lifestyle changes, alpha antagonists, 5-alpha reductase inhibitors, antimuscarinics, desmopressin and surgery are also described.