THE STUDY WAS CONDUCTED BETWEEN 1960 AND 1970. DATA PERTAINING TO THE PSYCHOSOCIAL DEVELOPMENT OF AGGRESSIVE BEHAVIOR WERE OBTAINED FROM A COUNTYWIDE POPULATION OF THIRD-GRADE SCHOOLCHILDREN AND THEIR PARENTS IN COLUMBIA COUNTY, NEW YORK. HYPOTHESES DEVELOPED FROM THIS FIRST WAVE OF FIELD SURVEY DATA WERE TESTED 10 YEARS LATER BY REINTERVIEWING THE SUBJECTS OF THE STUDY WHEN THEY WERE APPROXIMATELY 19 YEARS OF AGE. SINCE MEASUREMENTS OF AGGRESSIVE BEHAVIOR WERE OBTAINED DURING TWO TIME PERIODS -- CHILDHOOD AND YOUNG ADULTHOOD -- IT WAS POSSIBLE TO ISOLATE CERTAIN CHILD-REARING PRACTICES AND ENVIRONMENTAL CONDITIONS THAT APPEAR TO BE PREDICTORS OF AGGRESSIVE BEHAVIOR IN YOUNG ADULTHOOD. THESE FACTORS MAY INCLUDE EITHER EXCESSIVE PERMISSIVENESS OR HARSH PUNISHMENT BY THE CHILD'S PARENTS; A HIGH DEGREE OF SOCIAL MOBILITY; AND REJECTION OF THE CHILD BY HIS PEER GROUP. AS AN INTRODUCTION TO THE REPORT ON THIS STUDY, VARIOUS THEORIES OF AGGRESSION ARE DISCUSSED AND EVALUATED. THE DESIGN OF THE STUDY IS OUTLINED, AND MEASURES OF AGGRESSION USED AS ITS PRIMARY VARIABLES ARE DEFINED. THE VARIABLES AFFECTING THE DEVELOPMENT OF AGGRESSION FALL INTO THE CATEGORIES OF INSTIGATORS, CONTINGENT RESPONSES TO AGGRESSION, IDENTIFICATION VARIABLES, AND SOCIOCULTURAL VARIABLES. THE TWO QUESTIONNAIRES USED, ONE AT THE THIRD-GRADE LEVEL, THE OTHER AT THIRTEENTH GRADE, ARE REPRODUCED. THE ENVIRONMENTAL CONDITIONS WHICH ARE RELEVANT TO THE FORMATION OF AGGRESSIVE BEHAVIOR ARE DELINEATED, AND THE EFFECT OF THESE CONDITIONS ON THE DEVELOPMENT OF AGGRESSIVE BEHAVIOR IS EVALUATED FOR TWO MOMENTS IN TIME, 8 AND 19 YEARS OF AGE. DATA ARE CONSIDERED SEPARATELY FOR GIRLS AND BOYS, AS THIS AND OTHER STUDIES HAVE SHOWN THE EXISTENCE OF SIGNIFICANT DIFFERENCES IN AGGRESSIVE BEHAVIOR TO EXIST BETWEEN THE SEXES. A CHAPTER IS DEVOTED TO THE EFFECTS OF TELEVISION VIOLENCE ON BOYS AND GIRLS. THE RELATIONS WHICH WERE HYPOTHESIZED BETWEEN HIGH AGGRESSION AND PSYCHOPATHOLOGY AND BETWEEN LOW AGGRESSION AND POSITIVE SOCIAL OUTCOMES ARE ANALYZED. FINALLY, IMPLICATIONS OF THE RESULTS OF THIS STUDY FOR THEORY AND PRACTICE ARE EXPLORED. REFERENCES AND SUBJECT AND AUTHOR INDEXES ARE PROVIDED.