IN 4 SAMPLE WEEKS IN 1978 AND 1979, THE COURT APPEARANCE RECORDS OF 10,708 AND 12,400 DEFENDANTS WERE EXAMINED; THE RECORDS INCLUDED ALL DEFENDANTS APPEARING BEFORE THE CRIMINAL AND JUVENILE COURTS WITH NEW CHARGES DURING THE SAMPLE WEEK PERIODS. THE AGE CATEGORIES WERE JUVENILE (7-16 YEARS OF AGE), YOUNG ADULT (17-25 YEARS OF AGE), AND OLDER ADULT (26 AND OVER). OFFENSES WERE BROKEN DOWN INTO CRIMES AGAINST PERSONS, CRIMES AGAINST PROPERTY, NONASSAULTIVE SEX CRIMES, MAJOR MOTOR VEHICLE OFFENSES, PUBLIC ORDER OFFENSES, AND POSSESSION OR DISTRIBUTION OF CONTROLLED SUBSTANCES. THOUGH THE DATA REFLECT A HIGH CONCENTRATION (69.89 PERCENT) OF CRIMINAL AND DELINQUENT ACTIVITY IN THE UNDER-26 AGE GROUPS, THEY DO NOT NECESSARILY MEAN THAT YOUNG PEOPLE IN MASSACHUSETTS ARE THEREFORE MORE CRIMINAL THAN OLDER ADULTS. THE DEGREE OF SOPHISTICATION OF THE CRIMES MAY CHANGE, SINCE ADULTS HAVE A GREATER OPPORTUNITY FOR WHITE-COLLAR CRIMES AND THESE GO LARGELY UNDETECTED AND UNPROSECUTED. THE COST OF APPREHENSION AND THE DEGREE OF LAW ENFORCEMENT CONCENTRATION DIFFERS FROM THAT OF WHITE-COLLAR CRIMES. MANY OFFENSE CATEGORIES WERE FOUND TO BE AGE-LINKED; I.E., PATTERNS APPEARED WITH CERTAIN OFFENSES CHARACTERISTICALLY OVERREPRESENTED IN THE YOUNGER AGE CATEGORIES. THE LIMITED ECONOMIC OPPORTUNITIES FOR YOUNG ADULTS AND JVUENILES MAY BE RELATED TO THE HIGH INCIDENCE OF CERTAIN OFFENSES FOR THOSE AGE GROUPS. LIMITED ECONOMIC OPPORTUNITIES FOR FEMALES MAY ACCOUNT FOR THE OVERREPRESENTATION IN ECONOMICALLY RELATED OFFENSES. IN VIEW OF THE AGE-LINKAGE TO ECONOMIC CRIMES, ECONOMIC DOWNTURNS IN 1980 MAY REFLECT HIGHER CRIMINAL ACTIVITY BY THE GROWING LEGIONS OF UNEMPLOYED AND UNEMPLOYABLE, ESPECIALLY AMONG YOUNG PEOPLE AND WOMEN. BECAUSE OF THE HIGH REPRESENTATION OF YOUNG ADULTS, ANY DEMOGRAPHIC SHIFTS OVER TIME MAY HAVE A PROFOUND EFFECT ON THE FUTURE ARREST RATES. TABLES ILLUSTRATE THE DISTRIBUTION BY AGE AND SEX FOR THE OFFENSE CATEGORIES.