HISTORIC ATTITUDES TOWARD MENTALLY DEFICIENT OFFENDERS WERE REVIEWED, INCLUDING THE DEVELOPMENT OF IQ TESTING, CHANGING VIEWS ON THE RELATIONSHIP BETWEEN LOW INTELLIGENCE AND CRIMINALITY, AND THE IMPRECISION OF STATUTORY DEFINITIONS FOR DEFICIENT DELINQUENCY. THE SURVEY OBTAINED REPORTS ON THE IQ SCORES OF 90,477 INMATES IN U.S. CORRECTIONAL INSTITUTIONS. IT WAS FOUND THAT ABOUT 20,000 INMATES IN PENAL CORRECTIONAL INSTITUTIONS HAVE IQ SCORES BELOW 70. MOST COMMONLY, THESE INMATES HAD COMMITTED PROPERTY OFFENSES SUCH AS LARCENY OR BURGLARY. A GENERAL LACK OF SPECIALIZED PROGRAMING FOR RETARDED INMATES WAS REPORTED BY MOST INSTITUTIONS. INSTITUTIONS REPORTING AT LEAST 1 INMATE WITH AN IQ SCORE BELOW 55 WERE SELECTED FOR A FOLLOWUP SURVEY. DATA WERE OBTAINED FOR 964 SUCH INMATES FROM 26 INSTITUTIONS. THE OFFENSE PATTERNS REVEALED THAT 57 PERCENT WERE INCARCERATED FOR CRIMES AGAINST PERSONS. THE TWO MOST FREQUENT MANAGEMENT PROBLEMS CITED BY ADMINISTRATORS WERE THE INMATES' NEED FOR CONSTANT AND INDIVIDUAL STAFF ATTENTION AND THEIR TENDENCY TO BECOME VICTIMS OF EXPLOITATION BY THEIR MORE INTELLIGENT PEERS. ANOTHER FOLLOWUP STUDY INVESTIGATED THE RELATIONSHIP BETWEEN THE TYPE OF JUSTICE ADMINISTERED AND MENTALLY DEFICIENT DEFENDANTS. IN TWO-THIRDS OF THE 395 CASES EXAMINED, CONFESSIONS WERE OBTAINED, 59 PERCENT PLEADED GUILTY, AND 69 PERCENT WERE REPRESENTED BY COURT-APPOINTED COUNSEL. NO PRETRIAL PSYCHOLOGICAL TESTING WAS DONE IN 78 PERCENT OF THE CASES. ISSUES OF COMPETENCY TO STAND TRIAL WERE NOT RAISED IN 92 PERCENT OF THE CASES. ONLY 5 OF THE 34 RESPONDING STATES CITED PLANS WHICH INCLUDED SPECIALIZED FACILITIES OR TREATMENT FOR RETARDED OFFENDERS. CRITICAL ISSUES IDENTIFIED INCLUDE LACK OF AWARENESS OF THE COMPLEX LEGAL, SOCIOLOGICAL, AND PSYCHOLOGICAL PROBLEMS OF THE MENTALLY RETARDED AND LACK OF EMPIRICAL DATA ON THE RELATIONSHIP OF INTELLIGENCE AND ANTISOCIAL BEHAVIOR. MOREOVER, ADEQUATE SOCIOPSYCHOLOGICAL DEFINITIONS FOR DIAGNOSIS AND TREATMENT OF THIS OFFENDER GROUP ARE NEEDED, AS WELL AS ADEQUATE SERVICES. FOOTNOTES ARE INCLUDED.