The data base consists of 1,016 interviews (conducted by fire department staff) of juveniles and adults, most of whom were arrested between 1980 and 1984. The offenses included 504 arrests for arson; 303 for malicious false alarms; 159 for violations of laws related to fireworks, explosives, or bombings; and 50 for miscellaneous offenses. Computer-assisted analysis by the FBI's National Center for the Analysis of Violent Crime has developed statistically significant offender profiles based on the motive for the crime. The motives included vandalism (49 percent), excitement (25 percent), revenge (14 percent), other (8 percent), crime concealment (2 percent), and profit (1 percent). Juveniles generally committed crimes for excitement and vandalism, while adults tended to commit offenses for revenge or crime concealment. The majority of offenders were males. However, females committed many offenses to seek revenge. The use of alcohol, drugs, or both appeared to loosen an offender's inhibitions at the crime scene. Offenders often lived close to the crime scene, were accompanied by other persons, and returned to the crime scene later. The FBI and the county fire department plan to continue the research effort, which is using the most comprehensive data base available for these types of offenses. Data tables, photographs, and 12 footnotes.