Urinary retention is a common problem encountered in the emergency department. Acute urinary retention (AUR) presents as a sudden inability to voluntarily void, and is typically associated with lower abdominal pain. Its etiology can be varied and multifactorial. Treatment of AUR aims to relieve the obstruction and mitigate the underlying cause of retention. This can generally be accomplished in the emergency department without immediate urologic consultation; however, certain clinical features may require specialist involvement. This article provides an overview of the common causes of urinary retention, as well as emergency department evaluation, treatment, and disposition of patients with acute retention.