A QUESTIONNAIRE WAS SENT TO ALL STATE INSTITUTIONS FOR DELINQUENT GIRLS TO ASCERTAIN THE OFFENSES LEADING TO INSTITUTIONAL COMMITMENT. COMPARISONS WERE THEN MADE BETWEEN OTHER STATES AND THE STATE OF ILLINOIS ON THE FREQUENCY OF THESE OFFENSES. BASED ON A STUDY OF THESE 1971 AND 1972 STATISTICS, THE AUTHORS PERCEIVE DRAMATIC CHANGE IN THE CHARACTER OF FEMALE JUVENILE DELINQUENCY OFFENSES. ASSAULT, BURGLARY, AND ARMED ROBBERY WHICH IN THE PAST WERE CONSIDERED CHARACTERISTIC OF MALE OFFENSES ARE NOW COMMON AMONG FEMALE OFFENDERS, OTHER OFFENSES SUCH AS ARSON, AUTOMOBILE THEFT, ROBBERY, AND HOMICIDE ALSO ARE BEING COMMITTED MORE FREQUENTLY BY FEMALES. THE MAJOR PORTION OF THE TEST IS DEVOTED TO CASE HISTORIES OF DELINQUENT GIRLS AND DESCRIPTIONS OF THEIR SITUATIONS AS RELATED BY THE GIRLS, THEMSELVES. THESE CASES ARE ORGANIZED UNDER THE FOLLOWING PRINCIPLE OFFENSES: TRUANTS, RUNAWAYS INCORRIGIBLES, PROBATION-VIOLATORS, AND SEXUALLY DELINQUENT GIRLS. A BIBLIOGRAPHY FOLLOWS THE TEXT. (AUTHOR ABSTRACT MODIFIED)