CASE STUDIES, WHICH FOCUSED ON CRIMINAL CAREERS OF 49 INMATES SERVING TIME FOR ARMED ROBBERY IN A MEDIUM-SECURITY PRISON IN CALIFORNIA, PROVIDE DATA ON INDIVIDUAL OFFENSE RATES, PROBABILITIES OF ARREST, CONVICTION, INCARCERATION, AND MOTIVATION FOR CRIME. EVIDENCE WAS GATHERED FROM STRUCTURED INTERVIEWS WITH OFFENDERS AND FROM THEIR OFFICIAL CRIMINAL RECORDS. THE STUDY IDENTIFIED TWO HABITUAL OFFENDER TYPES: THE 'INTENSIVE,' WHO VIEWED HIMSELF AS A PROFESSIONAL, AND THE MORE FREQUENTLY ENCOUNTERED 'INTERMITTENT,' WHOSE CRIMINAL ACTIVITY HAD AN IRREGULAR AND OPPORTUNISTIC CHARACTER. INTENSIVES PURSUED THEIR CRIMINAL ACTIVITY WITH MUCH MORE PERSISTENCE AND SKILL THAN DID THE INTERMITTENTS. THE FORMER COMMITTED FAR MORE CRIMES THAN THE INTERMITTENTS, BUT THE INTERMITTENT OFFENDER WAS 5 TIMES MORE LIKELY TO BE ARRESTED. IN FACT, A MEAGER ARREST RECORD OFTEN IMPLIES A DANGEROUS CRIMINAL. THE STUDY FURTHER REVEALED THAT MOST HABITUAL OFFENDERS VIEWED THEIR CRIMES AS FREELY CHOSEN, AND ADMITTED THAT NEITHER REHABILITATION PROGRAMS NOR LONGER PRISON TERMS PROVIDED A STRONG INDUCEMENT TO END THEIR CRIMINAL CAREERS. THE STUDY SUGGESTS THAT SINCE MANY REHABILITATIVE AND PREVENTIVE PROGRAMS HAVE FALLEN SHORT OF EXPECTATION, EFFORTS SHOULD BE AIMED AT IMPROVING THE CRIMINAL JUSTICE SYSTEM. IDENTIFYING HABITUAL FELONS AND INCAPACITATING THEM BY INCARCERATION DURING THEIR ACTIVE YEARS MAY BE THE MOST EFFECTIVE WAY OF REDUCING CRIME. THIS WOULD AFFECT PRIMARILY YOUNG OFFENDERS, SINCE INDIVIDUAL OFFENSE RATES APPEAR TO DECLINE SUBSTANTIALLY WITH AGE. THE REPORT RECOMMENDS THAT MORE THOROUGH INFORMATION INCLUDING CRIME-CLEARANCE AND JUVENILE OFFENSE DATA BE PROVIDED TO IDENTIFY THE INTENSIVE OFFENDER. APPENDIXES INCLUDE THE INTERVIEW INSTRUMENT USED, AN EXAMINATION OF PREVIOUS STUDIES OF CRIMINAL CAREERS, AND A DISCUSSION OF THE USE OF SELF-REPORTED CRIME DATA.