Place roast in the crock pot. Pour the root beer all over the roast. Cover with lid and cook on low heat 10 to 12 hours OR cook on High heat 7 to 8 hours.
Carefully drain root beer from crock pot. Shred roast and remove any fat. Place shredded roast back in crock pot. Pour the barbecue sauce all over the meat. Stir. Cover with lid and cook 30 more minutes or until heated through.