There are two common causes of Acute Pancreatitis.

On common cause is gallstones, due to the passing of gallstones which become lodged in the common bile duct and become stuck within the Ampulla of Vater.

Gallstone Pancreatitis

Another common cause is alcohol consumption: Alcoholic Pancreatitis.

Less common are:

Traumatic Abdominal Injury, sustained from something such as a car wreck, bad fall, gunshot wound or a 200 pound full back slamming into your gut at full speed, is also a known cause of pancreatitis.

Cancer of the pancreas often causes pancreatitis.

AutoImmune Diseases can become a cause of a form of panc called AutoImmune Pancreatitis

Hypertriglyceridemia (hTG), unusally HIGH blood fat levels, Hypertriglyceridemia (hTG) can also cause of pancreatitis.

Other causes include medications such as Byetta (diabetes drug), exposure to certain chemicals, surgery and certain medical proceedures, infections like mumps, and pancreatic abnormalities.

I imagine there are other factors for causation as well.

And there is idiopathic pancreatitis which simply means doctors and the medical profession have no clue to the cause of your suffering.

More on Acute Pancreatitis and a list of common and not so common causes.

Pancreatitis, all about it.