The most serious inmates, those who concurrently commit robbery, assault, and drug dealing, disproportionately commit these defining crimes at high rates. They often commit burglaries, thefts, and other crimes at high rates, too -frequently at higher rates than other types of criminals, including those who specialize in those crimes. Unfortunately, information currently available from such sources as official arrest and conviction records do not permit criminal justice officials to distinguish meaningfully between these high-rate serious offenders and other types. Low-rate offenders can be more accurately identified using potentially available information on key characteristics: multiple drug use, unstable employment, juvenile use of hard drugs, and violence before the age of 16. (Author abstract)