Fibromyalgia (FM) is a common syndrome of functional somatic symptoms. This article examines whether an amplifying somatic style (increased body awareness and illness worry) might explain the distress and disability expressed by FM patients. Twenty FM patients were compared to twenty-three rheumatoid arthritis (RA) patients on measures of depressive and somatic symptomatology, pain, disability, and amplifying somatic style. FM patients reported greater somatic symptomatology, equivalent levels of pain, and less physical disability than did RA patients. No differences were observed between groups on body awareness or illness worry. Illness worry correlated highly with symptomatology for both groups but with physical disability only among FM patients. Results suggest that disability in functional somatic syndromes may be determined by patients' worry about having a serious disease. Feelings of vulnerability and apprehension about having an illness of unknown origin may contribute to FM sufferers' activity limitations, inability to sustain a work effort, and varied somatic distress.