Without thinking much about it, most of us expect that doctors will be able to “explain” our aches, pains, and complaints by finding some sort of tissue damage or disease that causes our discomfort. Despite such expectations, many of us have learned that not all physical suffering can be neatly explained by a physical examination or by medical tests and procedures. Doctors call physical disorders that are real but not caused by tissue damage “functional” disorders. Children with recurrent abdominal pain (RAP) and their families struggle with this sometimes frustrating and confusing situation every day. This article reviews characteristics, causes, and treatments.