THE CAMBRIDGE, ENGLAND, STUDY PROJECT REPRESENTS A LONG-TERM FOLLOWUP SURVEY OF APPROXIMATELY 400 BOYS. BOYS AND THEIR FAMILIES WERE FIRST CONTACTED IN 1961 WHEN THE BOYS WERE 8 YEARS OF AGE, AND PERSONAL CONTACT HAS BEEN MAINTAINED. SOME OF THE BOYS HAVE BEEN INTERVIEWED AT 21 YEARS OF AGE. ONE OF THE MAIN POINTS OF THE SURVEY WAS TO RELATE FACTORS MEASURED BEFORE 10 YEARS OF AGE AS THEY IMPACT ON SUBSEQUENT JUVENILE DELINQUENCY. AN EFFORT WAS MADE TO COLLECT AS MUCH INFORMATION AS POSSIBLE BEFORE THE BOYS REACHED THE AGE OF CRIMINAL RESPONSIBILITY AND COULD BE FOUND GUILTY IN COURT. BETWEEN 10 AND 17 YEARS OF AGE, 84 BOYS WERE FOUND GUILTY IN COURT FOR AN OFFENSE. MOST OFFENSES INVOLVED BURGLARY, THEFT, AND THE UNAUTHORIZED TAKING OF MOTOR VEHICLES AND MOST WERE COMMITTED WITH ONE OR TWO OTHER PERSONS, USUALLY BOYS OF THE SAME AGE. IN GENERAL, CRIMINAL CONVICTIONS TENDED TO RUN IN FAMILIES AND TO BE CONCENTRATED IN A SMALL MINORITY OF FAMILIES. FOUR THEORIES TO EXPLAIN THE ORIGINS OF JUVENILE DELINQUENCY ARE OUTLINED: (1) GENETIC THEORY; (2) SOCIAL LEARNING THEORY; (3) CULTURAL TRANSMISSION THEORY; AND (4) LABELING THEORY. IT IS ADVOCATED THAT EXPERIMENTS ON JUVENILE DELINQUENCY PREVENTION AND TREATMENT BE CONDUCTED IN ENGLAND THAT ARE BASED ON THEORIES ABOUT THE ROOTS OF DELINQUENT BEHAVIOR. THE ONLY WAY TO ESTABLISH THE RELATIVE EFFICACY OF ANY PREVENTION OR TREATMENT IS TO ALLOCATE PEOPLE RANDOMLY TO DIFFERENT TREATMENT GROUPS. (DEP)