The Cambridge Study in Delinquent Development was a prospective longitudinal survey of 411 males who were living in a working-class area of London at the time they were first contacted in 1961-62. The major aim of the study was to measure as many factors as possible alleged to be causes or correlates of offending. The theory of offending that the author develops from the findings of this study encompasses influences on antisocial tendency (long-term, between-individual) and influences on offending (short-term, within-individual) Influences on antisocial tendency, which begin in early childhood, are impulsivity, hyperactivity, sensation seeking, risk taking, and a poor ability to deter gratification. Other factors that influence antisocial tendency are poor ability to manipulate abstract concepts, low measured intelligence, low scholastic achievement, and low self-esteem. Influences on offending include an antisocial tendency, short-term situationally induced motivating factors, life circumstances or events, situational opportunities for offenders, and the costs and benefits of offending versus legitimate behavior. Under this theory, offending wanes and terminates with a decrease in antisocial tendency, which may be caused by a change in social influence from peers to spouses or girlfriends as well as changes in situational factors. 3 tables and 91 references