Many people are affected by urinary urgency, which can be highly bothersome. Urgency is the cornerstone symptom of overactive bladder (OAB), commonly occurring in conjunction with urinary frequency and nocturia. Once other medical causes of similar symptoms have been excluded, first-line OAB management comprises fluid intake advice and bladder training, supplemented by antimuscarinic drugs if necessary. Urodynamic confirmation of the diagnosis is required for OAB patients whose symptoms are refractory to first-line interventions. If patients are severely bothered by OAB despite optimization of medical treatment, they may proceed to invasive treatments, including neuromodulation, enterocystoplasty, detrusor myectomy, or urinary diversion. Our burgeoning understanding of the complex cellular, neural and integrative physiology of the bladder offers new insights into the causative mechanisms of OAB, and reasons why patients sometimes fail to respond to treatment. Study of sensory information pathways in the lower urinary tract has led to identification of the urothelium, afferent nerves and interstitial cells as key cellular elements in OAB. In-depth knowledge of the hierarchy of central nervous system control is lacking, but functional imaging is beginning to elucidate the challenges that lie ahead. New treatments under investigation include botulinum neurotoxin-A injection, oral β(3)-adrenergic agonists, and novel modalities for nerve stimulation. The subjective nature of urinary urgency, the lack of animal models and the multifactorial pathophysiology of OAB present significant challenges to effective clinical management.