Diverticular disease is one of the most common problems encountered by gastroenterologists, emergency physicians and surgeons, with a higher prevalence in elderly patients and a dramatic rising of incidences in young people, which involve an increase in health care costs, according to ambulatory visits and hospital admissions. Acute diverticulitis, the most important complication of diverticular disease, has a broad spectrum of severity, which involves many treatment options, ranging from outpatient-based antibiotic treatment, or even isolated nonsteroidal anti-inflammatory drugs, to parenteral antibiotic regimen, percutaneous drainage or surgery (lavage and drainage, Hartmann procedure or resection with anastomosis with or without a diverting stoma). The American Society of Colon and Rectal Surgeons recommended in their guidelines a routine follow-up colonoscopy after recovery from an acute episode to rule out malignancy, which is being re-evaluated in recent studies, including the alternative CT-colonography, especially in cases of incomplete colonoscopy or in high-risk patients. After an episode of acute diverticulitis, there is a significant risk of recurrence and a negative impact on quality of life. In order to decrease it, there are many treatments that are being evaluated such as fiber-rich diet, mesalazine, rifaximin, probiotics and elective colon resection, which should be decided individually. The aim of this book is to revise the current evidence about the diverticular disease and acute diverticulitis.