FROM 1940 TO 1943 THE LIFE STORIES OF 335 INMATES AT A DANISH MAXIMUM SECURITY PRISON WERE COMPILED. IT WAS FOUND THAT ENVIRONMENTAL FACTORS IN THE LIVES OF CHRONIC CRIMINALS WERE FAR MORE SEVERE THAN THOSE EXPERIENCED BY YOUNG ADULT FIRST OFFENDERS. ENVIRONMENTAL FACTORS ALSO SEEMED MORE IMPORTANT THAN PERSONALITY FACTORS IN DETERMINING AN OFFENDER'S PROGNOSIS. WORK WITH INMATES AT A SPECIAL INSTITUTION FOR PSYCHOPATHS SUPPORTED THE TENTATIVE CONCLUSION OF THE EARLIER STUDY THAT SITUATIONAL FACTORS WERE IMPORTANT DETERMINANTS OF CRIMINAL BEHAVIOR. FOUR CASE HISTORIES FROM THE SPECIAL INSTITUTUION'S FILES ILLUSTRATE THE VARIABILITY OF SYMPTOMATOLOGY FOUND IN OFFENDERS LABELED PSYCHOPATHS, THE CRUCIALITY OF SITUATIONAL VARIABLES IN DETERMINING BEHAVIOR, AND THE PROBLEMS THAT CAN ARISE WHEN CLINICIANS VIEW PSYCHOPATHY AS AN ENTITY WITH COMMON, STABLE PATTERNS OF REACTIONS. MOST OF THE DANISH OFFENDERS LABELED PSYCHOPATHS CHANGED THEIR BEHAVIOR OVER TIME, SOME DRAMATICALLY. PATTERNS OF ABNORMAL BEHAVIOR SEEMED TO BE DETERMINED BY BOTH EARLIER AND CURRENT SOCIAL EXPERIENCES. IT APPEARS THAT MOST CHRONIC CRIMINALS HAVE 'MASKS' OF PSYCHOPATHS--CHARACTER INSUFFICIENCIES THAT HINDER THEIR ABILITY TO DEAL WITH DEGRADING SOCIAL EXPERIENCES. THE PROGNOSIS FOR SUCH INDIVIDUALS IS MUCH BETTER THAN THAT FOR THE CLASSICAL PSYCHOPATH. WHAT REMAINS IS THE DEVELOPMENT OF MEANS TO DIFFERENTIATE BETWEEN THE HOPELESS PSYCHOPATHIC PERSONALITY AND THE CHRONIC CRIMINAL WHO HAS ADOPTED THE MASK OF A PSYCHOPATH. (LKM)