Achalasia, although rare, remains one of the most commonly diagnosed disorders of esophageal motility. It results from an idiopathic loss of ganglion cells responsible for esophageal motility and relaxation of the lower esophageal sphincter (LES). As a result, patients present with worsening dysphagia to both liquids and solids and often suffer from significant regurgitation of retained food in the esophagus. When the diagnosis of achalasia is suspected, patients should undergo evaluation with esophageal motility testing, endoscopic examination, and contrast esophagram. Once the diagnosis of achalasia has been established, options for treatment rely on controlling patient symptoms. Medical options are available, but their effectiveness is inconsistent. Endoscopic options include injection of botulinum toxin, which can achieve good short-term results, and pneumatic balloon dilation (PBD), considered the most effective non-surgical option. Surgical options, including laparoscopic, open, or endoscopic myotomy, and provide long-lasting results. This chapter will review achalasia and the treatment options available.