This article presents a selective review of psychosocial research on irritable bowel syndrome (IBS) in adults and on a possible developmental precursor, recurrent abdominal pain (RAP), in children. For IBS the authors provide a summary of epidemiology, of the psychological and psychiatric disturbances frequently found among IBS patients, and of the possible role of early abuse in IBS. A review of the psychosocial treatments for IBS finds strong evidence to support the efficacy of hypnotherapy, cognitive therapy, and brief psychodynamic psychotherapy. The research relating RAP to IBS is briefly reviewed, as is the research on its psychological treatment. Cognitive-behavioral therapy that combines operant elements and stress management has the strongest support as a treatment for RAP.