Review of the records of 191 nongeriatric state hospital inpatients showed that 50 (26%) of the patients had engaged in some form of fire-setting behavior; half of this group had engaged in a single episode. As a group, persons who had engaged in fire-setting behavior were significantly more likely to have a history of nonlethal self-injurious behavior and had a significantly greater number of admissions to the state hospital. The data suggest that fire setting by any patient cannot be accurately predicted and that fire-setting behavior may be an example of destructive operant behavior.